Short Answer

The model assigns a meaningfully lower probability than the market for Democrats winning by 3+ points (21.2% model vs 35.0% market). This divergence is likely driven by the district's structural Republican lean, despite expectations for an open seat and an unfavorable national environment to reduce the Republican margin of victory.

1. Market Behavior & Drivers

This market began with a very low probability, starting at just 1.0%, suggesting traders initially expected a large margin of victory, likely for the Republican incumbent. However, the price experienced a dramatic and rapid spike to a high of 37.0%. This sharp repricing appears to be a direct reaction to the news that incumbent Ryan Zinke announced he would not seek re-election. This development fundamentally changed the race from one with a known incumbent, who had previously won by a significant margin, to an open-seat contest. The creation of an open seat introduces considerable uncertainty and likely led traders to believe a closer election is much more probable, causing the massive upward adjustment in the contract's price.
Following the peak at 37.0%, the price has seen a minor pullback to its current level of 35.0%, indicating some stabilization after the initial volatile reaction. This suggests that 37.0% is acting as an early resistance level, while the market attempts to find a new consensus price. The overall trading volume of 563 contracts suggests a moderate level of interest in the market. The price shift from near zero to the mid-30s reflects a significant change in market sentiment, moving from a high degree of confidence in a wide margin to a belief that a closer outcome is now a distinct possibility.
  • MT-01 shows a structural Republican lean with R+5 PVI.
  • Ryan Busse (D) outpaced Aaron Flint (R) in total fundraising.
  • An open seat race is expected to reduce the Republican margin.
  • Unfavorable national trends likely reduce the Republican margin.
  • No reliable district-level polling is available for 2026.
  • Ryan Zinke (R) won MT-01 in 2024 by 7.7 percentage points.

Who Wins and Why

Outcome Market Model Why
Democrats, 9+ pts 11.0% 6.4% A projected unfavorable national environment is expected to reduce the Republican margin of victory.
Democrats, 3+ pts 35.0% 21.2% The shift to an open seat is expected to reduce the Republican margin of victory.
Democrats, 6+ pts 26.0% 15.4% Low presidential approval is expected to reduce the Republican margin of victory.

Current Context

Montana's 1st Congressional District will be an open seat in 2026. In the 2024 election, Republican Ryan Zinke defeated Democrat Monica Tranel in Montana's 1st District by an 8.7-point margin, securing 52.3% of the vote (168,529 votes) compared to Tranel's 44.6% (143,783 votes) [1][2]. However, a significant structural change for 2026 occurred when incumbent Ryan Zinke announced on March 2, 2026, that he would not seek re-election, creating an open-seat race for the district [3][4]. The key dates for the 2026 election include a filing deadline of March 4, 2026, a primary election on June 2, 2026, and the general election on November 3, 2026 [5][6][4].
Prediction markets currently lean Republican for the general election. Current prediction market sentiment suggests Republicans are favored to win the general election in Montana's 1st District, with one platform indicating an implied probability of 57% for Republicans versus 42% for Democrats [7]. A specific prediction market also exists for the "margin of victory" in MT-01, detailing scenarios such as "Republicans win... by 3+ pts" [8]. For the primary races, early signals from prediction markets show Aaron Flint leading the Republican primary with approximately 58% implied probability, while Ryan Busse holds a similar 58% lead in the Democratic primary [9][10].
Sources (10)
  1. 1Montana 1st District election results 2024 live updates | The Washington Postwashingtonpost.com
  2. 2Montana's 1st Congressional District election, 2024 - Ballotpediaballotpedia.org
  3. 3Western Montana U.S. Rep. Ryan Zinke won’t seek reelectionmontanafreepress.org
  4. 4Montana's 1st Congressional District election, 2026 (June 2 Republican primary) - Ballotpediaballotpedia.org
  5. 5Montana's 1st Congressional District election, 2026 - Ballotpediaballotpedia.org
  6. 6Montana's 1st Congressional District election, 2026 (June 2 Republican primary) - Ballotpediaballotpedia.org
  7. 7Montana Mic Drop: Zinke and Daines pull the plug on congressional careers - Montana Free Pressmontanafreepress.org
  8. 8Montana's 1st District margin of victory Odds & Predictionskalshi.com
  9. 9MT-01 Republican Primary Winner Predictions & Odds 2026 | Polymarketpolymarket.com
  10. 10MT-01 Democratic Primary Winner Predictions & Odds 2026 | Polymarketlmsh7.ggff.net

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Market Data

Contract Snapshot

The market resolves to "Yes" if the Democratic Party wins the 2026 U.S. House of Representatives election in Montana's 1st District by 3 percentage points or more; otherwise, it resolves to "No". The margin of victory is precisely calculated as the Democratic Party's vote percentage minus the closest opponent's, with no rounding applied, and verified by official election authorities. The market closes after the outcome occurs, potentially early if certified results are published, but no later than November 3, 2027, with payouts projected 30 minutes after closing.

Available Contracts

Market options and current pricing

Outcome bucket Yes (price) No (price) Last trade probability
Democrats, 3+ pts $0.36 $0.65 35%
Democrats, 6+ pts $0.26 $0.75 26%
Democrats, 9+ pts $0.11 $0.90 11%

Market Discussion

For the 2024 general election in Montana's 1st Congressional District, Zinke received 52.29% of the vote against Tranel's 44.62%, which implied a margin of approximately 7.67 points [1][2]. Prediction markets are actively tracking this race, with a dedicated "margin of victory" market available [3][4]. Separately, another market shows the Republican Party favored to win at 57% versus the Democratic Party at 42%, though this focuses on the winner rather than the specific margin [5].

Sources (5)
  1. 1Montana's 1st Congressional District election, 2024 - Ballotpediaballotpedia.org
  2. 22024 United States House of Representatives elections in Montanaen.wikipedia.org
  3. 3Montana's 1st District margin of victory Odds & Predictionskalshi.com
  4. 4Montana's 1st District margin of victory Odds & Predictions - Kalshikalshi.com
  5. 5MT-01 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com

4. Trust Index

Octagon Trust Index Kalshi 84 Good

Order book is critically thin.

Primary risk· Trade quality

How it adds up
Integrity80% of score93Strong
Trade quality20% of score47High Risk

Includes the cost to trade: a $1,000 order can't be filled here because the order book is too thin.

Trust score84Good

Weighted blend with hard caps — a critically weak safety pillar, or a severe trading anomaly, caps the total regardless of the rest. Full methodology · About the Trust Index

Trust profile
Integrity4 screens run · 6 don't apply
Market integrity
92Strong

Outcome is hard to influence

No suspicious activity on any screen

Screened clean
Large tradesNo single trade dominates the tape. Clear
Thin-volume movesMoves carried volume Clear
Size patternsTape too thin Clear
2 screens not run
Outcome control · doesn't apply to this market type
Thin-leg conviction · doesn't apply to this market type
Info fairness
95Strong

Structural prior — no screens apply

No suspicious activity on any screen

Screened clean
Information exposureNo concentrated group can know the outcome materially early. Clear
4 screens not run
Move vs. catalyst · doesn't apply to this market type
Longshot repricing · doesn't apply to this market type
Pre-broadcast certainty · doesn't apply to this market type
Cross-venue timing · doesn't apply to this market type
Resolution quality
92Strong

Resolution mechanism is dependable

No suspicious activity on any screen

Resolution rules read: Clear

Liquidity
59Thin

Expect slippage beyond small size

3 contracts · worst first

Forstag, 6+ pts40
Very thin · low confidence

Light recent trading — size may not fill near the screen price.

Forstag, 9+ pts52
Thin · low confidence

Light recent trading — size may not fill near the screen price.

Forstag, 3+ pts60
Thin · low confidence

Light recent trading — size may not fill near the screen price.

Book spread 69% vs realized 4%
Move quality
46Mixed

Some moves lacked volume

3 contracts · worst first

Forstag, 3+ pts46
Mixed · medium confidence

Volume opposes the move over 24h

Forstag, 6+ pts—
No significant move (24h)

Price was stable over the last 24 hours.

Forstag, 9+ pts—
No significant move (24h)

Price was stable over the last 24 hours.

Rule clarity
100Clear

Counts toward Resolution quality, not here

3 contracts · worst first

Forstag, 3+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Forstag, 6+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Forstag, 9+ pts100
Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Trade quality
47High Risk

Order book is critically thin

Tradable, but expect execution cost beyond small sizes.

Outcome quality 59 (notional-weighted across 3 scored legs)

$100 order: 38.6c slippage (~78% of a 49.5c contract)

$1,000 order: book too thin to fill

$10,000 order: book too thin to fill

Forstag, 3+ pts60Market scoreLiquidity60Move quality46Rule clarity100
Why 60
Liquidity
60 · Thin · low confidence

Light recent trading — size may not fill near the screen price.

Book spread 69% vs realized 4%
Move quality
46 · Mixed · medium confidence

Volume opposes the move over 24h

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Forstag, 6+ pts40Market scoreLiquidity40Move quality–Rule clarity100
Why 40
Liquidity
40 · Very thin · low confidence

Light recent trading — size may not fill near the screen price.

Move quality
No significant move (24h)

Price was stable over the last 24 hours.

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear
Forstag, 9+ pts52Market scoreLiquidity52Move quality–Rule clarity100
Why 52
Liquidity
52 · Thin · low confidence

Light recent trading — size may not fill near the screen price.

Move quality
No significant move (24h)

Price was stable over the last 24 hours.

Rule clarity
100 · Clear · high confidence

All checks pass

objective outcome · Clearofficial source · Cleartime boundary · Clear

underwriting_v1.4 · computed Sep 23, 2026

5. How do the fundraising totals for likely nominees Aaron Flint (R) and Ryan Busse (D) compare ahead of the general election?

Ryan Busse Fundraising Total$530,043.18 [1][2][3][4]
Aaron Flint Fundraising Total$453,653 [1][2][4]
Ryan Busse Cash on Hand$368,145.39 (as of March 31, 2026) [1][2][3][4]
Ryan Busse outpaced Aaron Flint in total fundraising efforts. The Democratic nominee, Ryan Busse, reported a fundraising total of $530,043.18 [1][2][3][4]. In comparison, the Republican nominee, Aaron Flint, raised $453,653 during the same period [1][2][4].
Aaron Flint holds a greater cash-on-hand advantage. As of March 31, 2026, Flint ended the first quarter with a cash-on-hand total of $429,000 [2][4]. Conversely, Busse reported $368,145.39 cash on hand by that date [1][2][3][4].
Sources (4)
  1. 1quiverquant.com
  2. 2montanafreepress.orgprojects.montanafreepress.org
  3. 3flatheadbeacon.com
  4. 4youtube.com

6. What do partisan lean indices and 2025-2026 voter registration data suggest for a Republican margin in an open-seat MT-01 race?

Cook PVI (MT-01)R+5 [1]
Cook Political Report RatingLikely Republican [1][2]
Polymarket Republican Odds57% [3]
Initial expectations for the MT-01 open-seat race indicate a Republican advantage. The district's Cook Partisan Voting Index (PVI) is R+5, signifying it is approximately five points more Republican than the national average [1]. This assessment is echoed by the Cook Political Report, which categorizes the seat as 'Likely Republican,' suggesting a clear Republican edge rather than a competitive toss-up scenario [1][2]. Further corroboration comes from Polymarket predictions, where traders price Republicans at 57% compared to Democrats at 42% for the 'MT-01 House Election Winner,' indicating a modest Republican lead that is more than a coin-flip but does not project a heavily favored candidate [3].
Montana's voter registration policies limit direct vote margin predictions from registration data. Directly inferring a vote-margin from 2025–2026 voter registration data for MT-01 is challenging because the state does not require voters to register by party [4]. Consequently, any party registration data available typically represents inferred or estimated partisan shares of the electorate rather than official party affiliations [4][5]. This characteristic restricts the ability to directly predict an MT-01 vote outcome from such data alone, as it would necessitate additional modeling for turnout and candidate-specific factors [4][5].
Sources (5)
  1. 1Montana's 1st Congressional District election, 2026 - Ballotpediaballotpedia.org
  2. 2MT-01 2026 | Cook Political Reportcookpolitical.com
  3. 3MT-01 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com
  4. 4Montana Voter Registration Statisticsindependentvoterproject.org
  5. 5The Cook Partisan Voting Index (Cook PVI℠) | Cook Political Reportcookpolitical.com

7. How might national political trends, such as presidential approval from June to November 2026, impact the final margin in Montana's 1st District?

Trump Approval (April 2026)43% approve (net

-12) [1]

Historical House Seat LossesAverage 27 seats (when presidential approval is near 43%) [2]
MT-01 Cook Partisan Voter IndexR+5 (heading into 2026) [3]
Presidential approval significantly influences Montana's 1st District election outcomes [4]. Declining approval for Donald Trump between June and November 2026 is projected to impact the final margin in Montana's 1st District (MT-01) [4]. Broader midterm political analysis suggests that a continued fall in Trump's approval through the autumn could lead to reduced Republican vote margins, including in MT-01's final result [5].
Weak presidential approval historically predicts substantial House seat losses [2]. Tracking in April 2026 reported Trump’s approval around 43% with a net -12, indicating weak approval that could benefit Democrats in the midterms [1]. Historically, presidential approval ratings at approximately 43% on Election Day have typically corresponded to significant House seat losses for the president’s party, averaging about 27 seats [2].
Montana's 1st District's partisan lean amplifies national shifts [3]. MT-01 has a modest Republican lean, as reflected by a Cook Partisan Voter Index of R+5 for 2026 [3]. This partisan tilt suggests that national shifts driven by presidential approval could meaningfully change the final district margin. Market expectations for MT-01's margin of victory are anticipated to adjust based on changes in the national House environment related to presidential approval [4].
Sources (5)
  1. 1Trump Approval Rating 2026 — Monthly Tracker & Historical Comparison | USPollingData.comuspollingdata.com
  2. 2Trump's Approval Rating: Why 43% Is the Key Number for 2026 | USPollingData.comuspollingdata.com
  3. 3Montana's 1st Congressional District election, 2026 (June 2 Republican primary) - Ballotpediaballotpedia.org
  4. 4Montana's 1st District margin of victory Odds & Predictionskalshi.com
  5. 5GOP midterm prospects darken as Trump approval falls | Brookingsbrookings.edu

8. Is there any reliable, public district-level polling for the MT-01 general election matchup available for the 2026 cycle?

Ryan Zinke Retirement DateMarch 2, 2026 [1][2]
Primary Election DateJune 2, 2026 [1][3][2]
General Election DateNovember 3, 2026 [1][3][2]
No reliable district-level polling is available for MT-01's 2026 general election. Currently, there is no reliable, publicly available district-level polling specifically for the Montana's 1st Congressional District general election matchup for the 2026 cycle. While a past fact mentioned a poll, its relevance to the general election significantly decreased when Representative Ryan Zinke announced his retirement on March 2, 2026, making the seat open. The research did not provide any specifics about this particular poll, including its results or public availability [1][2].
Election dates and potential matchups remain undetermined for the 2026 cycle. The final general election matchups for MT-01 are not yet established. Both the Democratic and Republican primaries for this district are scheduled for June 2, 2026, with the general election set for November 3, 2026 [1][3][2]. As of May 5, 2026, prediction market probabilities were available concerning a Republican win by specific margins; however, these represent market assessments rather than traditional polling data [4].
Sources (4)
  1. 1ballotpedia.org
  2. 2wikipedia.orgen.wikipedia.org
  3. 3ballotpedia.org
  4. 4kalshi.com

9. How did the final margins in comparable R-leaning, open-seat House races in 2022 and 2024 perform relative to their partisan lean?

Data for R-leaning open seats (2022/2024)Not available in provided information [1]
2022 House margin comparison (Ballotpedia)Available, but not restricted to open-seat R-leaning races [2]
2024 Average House margin of victory27.3 percentage points (overall) [3]
Specific data determining final margins in comparable R-leaning, open-seat House races for 2022 and 2024, relative to their partisan lean, is not available. The provided research output lacks the necessary filtered subsets to fully address how these particular races performed. While available resources discuss methodologies for measuring performance, the granular details for 'comparable R-leaning open seats' were not present in the snippets.
For 2022, available data does not specify open-seat races. Ballotpedia offers a comparison between 2020 presidential margins and 2022 U.S. House margins across all districts, which could serve as a general method for assessing performance relative to partisan lean [2]. However, this information is not restricted to open-seat races and does not specifically summarize the subset of 'comparable R-leaning open seats' required for this analysis [2].
Similarly, 2024 data lacks specific subset comparison for R-leaning open seats. Ballotpedia's congressional margin-of-victory analysis provides overall averages, such as an average U.S. House margin of victory of 27.3 percentage points in 2024 [3]. While a 2024 U.S. House results page lists 2020 Presidential margins, 2022 U.S. House margins, and open-seat status for many districts, computing the final margins for the precise criteria of 'comparable R-leaning, open-seat races' would necessitate further filtering and comprehensive table extraction not provided in the snippets [4]. Furthermore, market pages for specific districts, such as Montana's 1st District on Kalshi, do not contain the necessary 2022/2024 historical comparative performance data [1][5].
Sources (5)
  1. 1Montana's 1st District margin of victory Odds & Predictionskalshi.com
  2. 2Election results, 2022: Comparison of 2020 presidential and 2022 U.S. House midterm results - Ballotpediaballotpedia.org
  3. 3Election results, 2024: Congressional margin of victory analysis - Ballotpediaballotpedia.org
  4. 4Election results, 2024: U.S. House - Ballotpediaballotpedia.org
  5. 5Montana's 1st District margin of victory — Elections odds compared | OddsBridge — OddsBridgeoddsbridge.app

10. What Could Change the Odds

Key Catalysts

In the 2024 Montana-01 general election, Ryan Zinke (R) won with 52.3% of the vote compared to Monica Tranel (D) at 44.6%, resulting in a 7.7 percentage point margin of victory [1][2][3]. For the 2026 U.S. House election, a market is available that resolves based on whether the Republican Party secures a victory by at least 3 percentage points [4][5].
Current Polymarket odds for the MT-01 House election winner indicate a 57% probability for the Republican candidate and 42% for the Democratic candidate, with resolution around Nov 4, 2026 [6]. Nevertheless, local reporting preceding the 2026 cycle highlighted a low approval rating for Ryan Zinke, with only 26% approving and 41% being neutral or unfamiliar, suggesting a potential opportunity for Democrats if support is perceived to be softening [7].

Key Dates & Catalysts

  • Expiration: November 03, 2027
  • Closes: November 03, 2027
Sources (7)
  1. 1Montana U.S. House - District 1 Election Results | USA TODAYusatoday.com
  2. 2Republican Montana Rep. Ryan Zinke wins re-election in state's 1st Congressional District | Fox Newsfoxnews.com
  3. 3Montana's 1st Congressional District - Ballotpediaballotpedia.org
  4. 4Montana's 1st District margin of victory Odds & Predictionskalshi.com
  5. 5Montana's 1st District margin of victory Odds & Predictions - Kalshikalshi.com
  6. 6MT-01 House Election Winner Predictions & Odds 2026 | Polymarketpolymarket.com
  7. 7All eyes on western Montana as 2026 midterms approach | Daily Inter Lakedailyinterlake.com