# CA-04 House winner?

In 2026

Updated: September 14, 2026

Category: Elections

Tags: House, US Elections

HTML: /markets/elections/house/ca-04-house-winner/

## Short Answer

**Key takeaway.** Mike Thompson is likely to win the CA-04 House seat in 2026, with the **market** pricing this outcome at **66.0%** while the **model** shows a higher **79.9%** **probability**.

## Key Claims (September 2026)

**- - Mike Thompson, a 14-term Democratic incumbent, benefits from CA-04's partisan advantage.** - Eric Jones initially created a cash-on-hand advantage through significant self-funding.
- No reliable public polling data exists for the 2026 CA-04 head-to-head matchup.

## Market Behavior & Drivers

Mike Thompson's **$4.2** million fundraising, reported in July 2026 FEC filings, strongly supports his incumbent advantage.

The primary driver for this market's pricing is the structure of the general election. The race for California's 4th Congressional District is a contest between incumbent Democrat Mike Thompson and fellow Democrat Eric Jones. This intra-party dynamic prevents the market from pricing the incumbent as a prohibitive favorite, as he faces a challenger from his own party rather than a Republican in a district that favors Democrats.

The market's downward drift in September, with the price falling from 75% to 66%, appears to be a direct repricing of the incumbent's odds in this specific matchup. A contest between two candidates from the same party introduces different variables and a higher degree of uncertainty than a standard partisan election. The provided data shows zero trade volume accompanying this price drop, which suggests the adjustment may reflect shifting offers based on new information rather than active trading pressure.

### Who Wins and Why

| Outcome | Market | Model | Why |
| --- | --- | --- | --- |
| Mike Thompson | 66.0% | 79.9% | Incumbent Mike Thompson has a long congressional record and strong fundraising in a Democratic-leaning district. |
| Eric Jones | 29.0% | 20.1% | Eric Jones faces an uphill battle with limited fundraising and name recognition in a heavily Democratic district. |

## Model vs Market

| Outcome | Market Probability | Octagon Model Probability |
| --- | --- | --- |
| Mike Thompson | 66.0% | 79.9% |
| Eric Jones | 29.0% | 20.1% |

- Expiration: November 3, 2027

## Significant Price Movements

#### 📉 September 14, 2026: 60.0pp drop

Price decreased from 89.0% to 29.0%

**Outcome:** Eric Jones

**What happened:** The provided research does not contain information to identify the primary driver of a 60.0 percentage point drop in Eric Jones' prediction market price for the CA-04 House election on September 14, 2026. As of that date, the general election for California's 4th Congressional District had not yet occurred, being scheduled for November 3, 2026 [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026). There is no mention of social media activity, traditional news, or market structure factors in the provided sources that would explain such a movement. Therefore, based on the available data, social media's role as a primary driver, accelerant, or noise cannot be determined.

## Contract Snapshot

This market resolves YES if Mike Thompson wins the CA-04 House election, and NO if he does not. The market begins on November 3, 8:00 AM EST, with the maximum payout date set for November 3, 2027. No special settlement conditions are explicitly stated in the provided content.

## Market Discussion

The general election for California's 4th Congressional District is scheduled for November 3, 2026 [[^]](https://www.nbcnews.com/politics/2026-primary-elections/california-us-house-district-4-results)[[^]](https://www.nytimes.com/interactive/2026/us/elections/results-california-us-house-4-primary.html)[[^]](https://theballotbook.com/election_reports/2026/primary/24598560). Incumbent Democrat Mike Thompson and Democratic challenger Eric Jones advanced to the general election after the June 2, 2026, top-two primary [[^]](https://www.nbcnews.com/politics/2026-primary-elections/california-us-house-district-4-results)[[^]](https://www.nytimes.com/interactive/2026/us/elections/results-california-us-house-4-primary.html)[[^]](https://theballotbook.com/election_reports/2026/primary/24598560)[[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/)[[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary). Prediction markets overwhelmingly favor incumbent Mike Thompson to win the CA-04 general election, often showing implied probabilities exceeding 80% over Eric Jones [[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://polymarket.com/event/ca-04-house-election-winner).

## Market Data

| Contract | Yes Bid | Yes Ask | Last Price | Volume | Open Interest |
| --- | --- | --- | --- | --- | --- |
| Eric Jones | 29% | 32% | 29% | 16,340 contracts | 10,636 contracts |
| Mike Thompson | 68% | 69% | 66% | 23,298 contracts | 6,321 contracts |

## How do Mike Thompson's and Eric Jones's 2026 campaign platforms and key endorsements compare?

Thompson Primary Vote | 40.97% (June 2, 2026 primary) [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary) |
Jones Primary Vote | 22.23% (June 2, 2026 primary) [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary) |
Thompson Prediction Market Odds | 71% to 90% chance of winning (late July/early August 2026) [[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://www.predictionhunt.com/odds/ca-04-house-winner/11934)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027) |

**Mike Thompson and Eric Jones present contrasting platforms and endorsements for the 2026 election**

Mike Thompson and Eric Jones present contrasting platforms and endorsements for the 2026 election. Mike Thompson, a 14-term Democratic incumbent, centers his 2026 campaign on his extensive legislative experience, dedication to constituent services, and agricultural policy [[^]](https://www.capradio.org/articles/2026/06/01/what-to-know-about-congressional-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary))[[^]](https://davisite.org/2026/04/19/who-is-eric-jones-the-candidate-seeking-to-unseat-mike-thompson-in-congress/). His key endorsements include prominent Democratic figures such as Governor Gavin Newsom and Senators Alex Padilla and Adam Schiff [[^]](https://www.capradio.org/articles/2026/06/01/what-to-know-about-congressional-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary))[[^]](https://davisite.org/2026/04/19/who-is-eric-jones-the-candidate-seeking-to-unseat-mike-thompson-in-congress/). In contrast, Eric Jones, a venture capitalist and tech entrepreneur, is running on an anti-establishment platform that advocates for Medicare for All, an aggressive housing expansion aiming for 2 million new homes, and structural government reforms [[^]](https://www.capradio.org/articles/2026/06/01/what-to-know-about-congressional-district-4-race/)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary))[[^]](https://davisite.org/2026/04/19/who-is-eric-jones-the-candidate-seeking-to-unseat-mike-thompson-in-congress/). Jones's endorsements include Our Revolution, Indivisible Yolo, and a notable cross-party endorsement from Republican primary candidate Ray Riehle [[^]](https://www.capradio.org/articles/2026/06/01/what-to-know-about-congressional-district-4-race/)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary))[[^]](https://davisite.org/2026/04/19/who-is-eric-jones-the-candidate-seeking-to-unseat-mike-thompson-in-congress/)[[^]](https://www.pressdemocrat.com/2026/08/17/surprising-congressional-endorsement-for-eric-jones-republican-ray-riehle-who-he-beat-in-june/).

Primary election results and subsequent forecasts strongly favor Mike Thompson in the general election. In the June 2, 2026 primary election, Mike Thompson secured approximately **40.97%** of the vote, while Eric Jones received about **22.23%** [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary). Following the primary, election forecasters have rated the 2026 general election for California's 4th Congressional District as Solid/Safe Democratic [[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/). Prediction markets, as of late July/early August 2026, also heavily favor Mike Thompson to win, with his odds ranging from **71%** to **90%** against Eric Jones [[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://www.predictionhunt.com/odds/ca-04-house-winner/11934)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027).

## How do historical election results in CA-04, particularly after the last redistricting, support its 'Safe Democratic' rating?

Cook PVI | D+17 [[^]](https://en.wikipedia.org/wiki/California%27s_4th_congressional_district)[[^]](https://polymarket.com/event/ca-04-house-election-winner)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024_(March_5_top-two_primary))[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary)) |
2022 Democratic Vote Share | 67.8% [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast) |
2026 Democratic Win Probability (Forecast) | >99% [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast) |

**California's 4th Congressional District consistently demonstrates a strong Democratic partisan advantage**

California's 4th Congressional District consistently demonstrates a strong Democratic partisan advantage. This is largely due to its robust partisan composition and historical election performance. After the 2020 redistricting, the district shows an approximate voter registration advantage of **42%** Democratic to **30%** Republican [[^]](https://en.wikipedia.org/wiki/California%27s_4th_congressional_district)[[^]](https://polymarket.com/event/ca-04-house-election-winner)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024_(March_5_top-two_primary))[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary)). Furthermore, it holds a Cook Partisan Voter Index (PVI) of D+17, indicating that the district is 17 percentage points more Democratic than the national average based on recent presidential election results [[^]](https://en.wikipedia.org/wiki/California%27s_4th_congressional_district)[[^]](https://polymarket.com/event/ca-04-house-election-winner)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024_(March_5_top-two_primary))[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary)). This strong Democratic preference was evident in the 2022 general election, where the Democratic candidate won with **67.8%** of the vote [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast).

Analysts and prediction markets consistently forecast a decisive Democratic victory in CA-04. For the 2026 election cycle, major election analysts, including the Cook Political Report and Decision Desk HQ, classify CA-04 as 'Solid D' or 'Safe Democratic' [[^]](https://www.cookpolitical.com/ratings/house-race-ratings)[[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast). Forecasts from Decision Desk HQ further underscore this strong Democratic position, assigning a win **probability** exceeding **99%** to the Democratic candidate [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2024)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast). Prediction markets for the 2026 CA-04 House race consistently favor the incumbent, Mike Thompson, with implied win probabilities typically ranging from **71%** to **84%** [[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://www.quiverquant.com/election-fundraising/house/CA/4)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503). Notably, the general election for CA-04 in 2026 will feature an all-Democratic runoff between incumbent Mike Thompson and challenger Eric Jones, as no Republican candidates advanced [[^]](https://polymarket.com/event/ca-04-house-election-winner)[[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503).

## What potential catalyst before November 2026, such as a major gaffe or scandal, could significantly alter the current forecast for the CA-04 election?

Incumbent's Predicted Win Probability | Over 99% [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://www.predictionhunt.com/odds/ca-04-house-winner/11934)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets) |
Challenger's Self-Funding | Eric Jones self-funded $5 million [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503) |
Election Forecast Rating | Solid or Safe Democratic [[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/) |

**Incumbent Mike Thompson is overwhelmingly favored for the CA-04 election**

Incumbent Mike Thompson is overwhelmingly favored for the CA-04 election. Current prediction **market** forecasts indicate a win **probability** exceeding **99%** for Thompson in the CA-04 House election [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://www.predictionhunt.com/odds/ca-04-house-winner/11934)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets). Although implied probabilities for Thompson ranged from **70%** to **90%** in late July and August 2026, he remains the overwhelming favorite in this all-Democratic contest against challenger Eric Jones [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://polymarket.com/event/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://www.predictionhunt.com/odds/ca-04-house-winner/11934)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/). Election forecasters consistently rate the race as Solid or Safe Democratic [[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/).

No significant catalysts are identified to alter current forecasts. Eric Jones, who advanced through California's top-two primary system, is notably supporting his campaign with **$5** million of his own funding [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://news.ballotpedia.org/2026/06/15/incumbent-mike-thompson-d-and-eric-jones-d-advanced-from-the-top-two-primary-for-californias-4th-congressional-district-on-june-2-2026/). However, Thompson's long tenure and institutional backing continue to make him the favored candidate. Prediction markets and election forecasters do not identify any specific catalysts or public scandals widely expected to significantly alter the current **market** consensus before the November 2026 election [[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/).

## Is there any reliable public polling data from 2026 that measures the head-to-head matchup between Mike Thompson and Eric Jones in CA-04?

Mike Thompson Prediction Market Probability | 76-90% (to win CA-04 House seat) [[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/) |
Mike Thompson Primary Vote Share | 40.97% (June 2, 2026 primary) [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary) |
Eric Jones Primary Vote Share | 22.23% (June 2, 2026 primary) [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary) |

**No reliable public polling data exists for the CA-04 race**

No reliable public polling data exists for the CA-04 race. As of late 2026, there is no widely reported or reliable public polling data from 2026 measuring a head-to-head matchup between Mike Thompson and Eric Jones in California's 4th Congressional District [[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://kalshi.com/markets/kxcaelection/california-general-elections-/kxcaelection-2604)[[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary). Consequently, election tracking for this race primarily relies on prediction **market** data and political analysis [[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://kalshi.com/markets/kxcaelection/california-general-elections-/kxcaelection-2604)[[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/).

Prediction markets strongly favor incumbent Mike Thompson's re-election. As of mid-September 2026, prediction markets consistently indicate incumbent Mike Thompson is favored to win the CA-04 House seat, with implied probabilities for his victory generally ranging between **76%** and **90%** across various platforms [[^]](https://www.predictionedge.com/elections/us-house/california-district-4-race/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027)[[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/). In the California top-two primary held on June 2, 2026, Mike Thompson received **40.97%** of the vote, while Eric Jones received **22.23%** [[^]](https://votes.decisiondeskhq.com/races/2026-06-02/california-us-house-4-primary).

Thompson and Jones are certified candidates in a safely Democratic district. Incumbent Mike Thompson and challenger Eric Jones, both Democrats, are the certified candidates for the California 4th Congressional District (CA-04) general election scheduled for November 3, 2026 [[^]](https://ballotpedia.org/California%27s_4th_Congressional_District_election,_2026_(June_2_top-two_primary))[[^]](https://elections.cdn.sos.ca.gov/statewide-elections/2026-general/cert-list-candidates.pdf)[[^]](https://www.kcra.com/article/california-june-election-results-us-house-district-4-results/71575854). Decision Desk HQ forecasts a greater than **99%** **probability** for a Democrat to win the California 4th District House seat, categorizing it as a Safe Democratic race [[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast)[[^]](https://integration-votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets).

## What do the 2026 FEC fundraising reports indicate about Mike Thompson's financial advantage in this race?

Mike Thompson Total Raised | ~$4.2 million (2026 election cycle) [[^]](https://www.fec.gov/data/candidate/H8CA01109/)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast) |
Eric Jones Self-Funding | $5 million (April and May 2026) [[^]](https://www.fec.gov/data/candidate/H8CA01109/)[[^]](https://napavalleyregister.com/news/fourth-district-campaign-finance/article_ef09ff4c-f373-42a9-afe4-980c27c8892e.html)[[^]](https://www.pressdemocrat.com/2026/05/29/jones-campaign-money-thompson-district4/) |
Mike Thompson Win Probability | >99% (as of Sept 11, 2026) [[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast) |

**Eric Jones's significant self-funding initially created a cash-on-hand advantage**

Eric Jones's significant self-funding initially created a cash-on-hand advantage. As of the July 2026 quarterly FEC reports, Mike Thompson had raised over **$4.2** million for California's 4th Congressional District 2026 election cycle [[^]](https://www.fec.gov/data/candidate/H8CA01109/)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast). His Democratic challenger, Eric Jones, notably altered the financial landscape by self-funding **$5** million of his campaign through major contributions in April and May 2026 [[^]](https://www.fec.gov/data/candidate/H8CA01109/)[[^]](https://napavalleyregister.com/news/fourth-district-campaign-finance/article_ef09ff4c-f373-42a9-afe4-980c27c8892e.html)[[^]](https://www.pressdemocrat.com/2026/05/29/jones-campaign-money-thompson-district4/). This self-funding resulted in Jones holding a cash-on-hand advantage of nearly **$4.3** million before the June 2, 2026 primary, compared to Thompson's **$1.7** million [[^]](https://www.pressdemocrat.com/2026/05/29/jones-campaign-money-thompson-district4/).

Despite the financial shift, Mike Thompson remains favored in prediction markets. Despite Eric Jones' substantial self-funding efforts, prediction markets consistently favor Mike Thompson to win the general election [[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027). As of mid-2026, implied probabilities for Thompson's victory often ranged from **75%** to **90%** [[^]](https://robinhood.com/us/en/prediction-markets/elections/events/ca-04-house-winner-nov-03-2026/)[[^]](https://www.lines.com/prediction-markets/elections/ca-04-house-election-winner-by-individual-20260630172946503)[[^]](https://predictmarketcap.com/events/who-will-win-the-2026-ca-04-house-election-nov-3-2027). Furthermore, Decision Desk HQ forecasted Mike Thompson with a >**99%** **probability** of securing the CA-04 House seat as of September 11, 2026, classifying the district as 'Safe Democratic' [[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/markets)[[^]](https://votes.decisiondeskhq.com/races/2026-11-03/california-us-house-4-general-election/forecast).

## What Could Change the Odds

**Prediction markets currently assign a high probability (approximately 85-88%) to the Democratic Party winning control of the U.S.** House in 2026 [[^]](https://www.stokastic.com/articles/prediction-markets/house-control-odds)[[^]](https://www.ainvest.com/news/house-majority-illusion-88-pricing-ignores-fine-print-2609/)[[^]](https://polymarket.copilot.markets/event/which-party-will-win-the-house-in-2026). The 2026 United States House of Representatives elections are scheduled for Tuesday, November 3, 2026 [[^]](https://en.wikipedia.org/wiki/2026_United_States_House_of_Representatives_elections)[[^]](https://ballotpedia.org/United_States_Congress_elections,_2026).

**Key takeaway.** Bullish catalysts for Democrats include the historical midterm penalty for the president's party, strong generic-ballot polling, and special election overperformances [[^]](https://www.stokastic.com/articles/prediction-markets/house-control-odds)[[^]](https://www.predictionhunt.com/news/2026-house-control-bets-hit-684k-in-one-day-10x-sep-10-2026)[[^]](https://www.electionodds.com/house/)[[^]](https://www.ainvest.com/news/house-majority-illusion-88-pricing-ignores-fine-print-2609/).

**Key takeaway.** Bearish catalysts include redistricting map advantages for Republicans and potential legal challenges to district lines [[^]](https://www.stokastic.com/articles/prediction-markets/house-control-odds)[[^]](https://www.predictionhunt.com/news/2026-house-control-bets-hit-684k-in-one-day-10x-sep-10-2026)[[^]](https://www.electionodds.com/house/)[[^]](https://www.ainvest.com/news/house-majority-illusion-88-pricing-ignores-fine-print-2609/).

## Key Dates & Catalysts

- **Expiration:** November 03, 2027
- **Closes:** November 03, 2027

## Decision-Flipping Events

- Prediction markets currently assign a high **probability** (approximately 85-**88%**) to the Democratic Party winning control of the U.S.
- House in 2026 [^] [^] [^] .
- The 2026 United States House of Representatives elections are scheduled for Tuesday, November 3, 2026 [^] [^] .
- Bullish catalysts for Democrats include the historical midterm penalty for the president's party, strong generic-ballot polling, and special election overperformances [^] [^] [^] [^] .

## Related Research Reports

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## Historical Resolutions

No historical resolution data available for this series.

## Disclaimer

This content is for informational and educational purposes only and does not constitute financial, investment, legal, or trading advice.
Prediction markets involve risk of loss. Past performance does not guarantee future results.
We are not affiliated with Kalshi or any prediction market platform. Market data may be delayed or incomplete.

### Data Sources & Model Transparency

**Data Sources:** Octagon Deep Research aggregates information from multiple sources including news, filings, and market data.

**Freshness:** Analysis is generated periodically and may not reflect the latest developments. Verify critical information from primary sources.

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