Short Answer

Both the model and the market overwhelmingly agree that Keir Starmer's departure will be announced before Dec 1, 2026, with only minor residual uncertainty.

1. Market Behavior & Drivers

This market's price has been mostly flat, trading near zero percent probability for most of its duration before experiencing extreme volatility. The price action is characterized by a major spike on June 20, 2026, where the probability jumped by 16.0 percentage points from 2.0% to 18.0%. This was immediately followed by a sharp reversal on June 21, with a 17.0 percentage point drop from a high of 22.0% down to 5.0%. The market has traded within a range of 0.0% to a peak of 29.0%. The overall trading volume of 26,652 contracts is concentrated around this recent period of volatility, with a significant increase in trading activity on June 21.
The significant price movements were directly driven by news reports regarding Prime Minister Keir Starmer's political future. The initial price surge on June 20 was a reaction to multiple reports that he was expected to announce a timetable for his departure. The subsequent price drop on June 21 occurred amid similar widespread reporting that he was actively considering his exit. This sharp reversal suggests that while the initial news caused a speculative spike, the market's conviction waned, or traders began to doubt the immediacy of an official announcement. The concentration of trading volume during these two days indicates high market engagement and conviction tied directly to the news cycle, as traders actively priced in the breaking developments.
The chart suggests that the market had previously assigned almost no chance of a departure announcement, with the price acting as a firm support level at 0.0%. The recent news established a clear, albeit brief, resistance level near the 29.0% peak, which traders were unwilling to push past. The current price of 5.0% suggests that despite intense political pressure and media speculation, overall market sentiment is now highly skeptical that an official departure will be announced. The initial speculative fervor has faded, replaced by a much lower probability assessment.
  • Since last update (~24h): The model dramatically raised odds for departure Before Jun 27, 2026 by +61.3pp, flipping the edge.
  • For departure Before Jun 22, 2026, the model's -14.4pp probability decrease was market-led.
  • The overall headline edge compressed by +0.6pp, indicating model-market alignment improved.
  • Two new outcomes, 'Before Jul 23, 2026' and 'Before Jul 24, 2026', were added.
  • Keir Starmer is widely expected to announce a departure timetable.
  • Reports indicate this timetable may be set as early as June 22, 2026.
  • Likelihood of an announcement occurring before June 22, 2026, is reduced.
  • Starmer faces significant pressure following a recent by-election loss.
  • Andy Burnham appears more favorable than Starmer as Labour leader.
  • Past Prime Minister resignations often follow peak crises within two days.

Who Wins and Why

Outcome Market Model Why
Before Oct 1, 2026 97.0% 95.9% Research does not highlight strong supporting evidence.
Before Nov 1, 2026 98.0% 97.3% Research does not highlight strong supporting evidence.
Before Dec 1, 2026 99.0% 98.6% Keir Starmer is widely expected to announce a timetable for his departure due to political pressure.

Current Context

Prime Minister Keir Starmer faces intense pressure to resign from office. As of June 21, 2026, Prime Minister Keir Starmer has not yet officially resigned, but significant political pressure is mounting for his departure. Reports indicate he is expected to announce a timetable for his resignation as early as Monday, June 22, 2026 [1][2][3][4][5].
Political realities and a by-election loss fuel Starmer's leadership crisis. Starmer’s cabinet ally, Business Secretary Peter Kyle, stated that the Prime Minister is 'reflecting on political realities' and the challenges confronting his leadership, which is widely interpreted as a sign that he is contemplating stepping down [4][6][7]. This current political crisis was largely driven by Andy Burnham’s decisive victory in the Makerfield by-election, an event that significantly weakened Starmer's authority and intensified calls from Labour MPs and cabinet ministers for an orderly leadership transition [2][4][6].
Broader UK political instability could impact bond markets. The political difficulties faced by Keir Starmer, and any potential challenger, worry bond markets [8]. More broadly, the state of UK politics is a recurring topic, with discussions touching on the trauma it presents, its potential impact on bond markets and "full faith and credit" papers, and its implications for the UK's overall credibility and economics in the coming days and months [9][10][11][12].
Sources (12)
  1. 1Report says UK PM Starmer ready to quit, but source says he is still...reuters.com
  2. 2Signs grow that Starmer will set out timetable to resign as mood in government shifts - BBC Newsbbc.co.uk
  3. 3Signs grow that Starmer will resign as government mood shiftsbbc.com
  4. 4Starmer reflecting on political reality as he considers future, says allybbc.com
  5. 5Keir Starmer expected to announce departure as prime minister on...theguardian.com
  6. 6Starmer is on the precipice as pressure builds for the UK leader to resign | The Independentindependent.co.uk
  7. 7Starmer reflecting on ‘political realities’ amid pressure to resign | The Independentindependent.co.uk
  8. 8Wall Street Week | Britain’s Debt Problem, Poland’s Economic Boomyoutube.com
  9. 9Inflation Data and Market Bullishness | Bloomberg Surveillanceyoutube.com
  10. 10Daybreak Weekend: US PCE, London Climate | Bloomberg Daybreak: US Editionyoutube.com
  11. 11EMERGENCY DEBATE: The Death Of The Middle Class! Only The Top 1% Will Survive!youtube.com
  12. 12Daybreak Weekend: Fed Meeting, UK Election, BOJ Decision | Bloomberg Daybreak: US Editionyoutube.com

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Significant Price Movements

Notable price changes detected in the chart, along with research into what caused each movement.

Outcome: Before Jul 23, 2026

📈 June 21, 2026: 75.0pp spike

Price increased from 15.0% to 90.0%

What happened: The primary driver of this price movement was widespread traditional news reporting on June 20 and 21, 2026, indicating that UK Prime Minister Keir Starmer was actively considering his departure [1][2][3][4]. Numerous major outlets reported Starmer was expected to announce his resignation or an exit timetable as early as Monday, June 22, 2026, following internal Labour Party pressure after a by-election defeat [1][3][4][5]. This breaking news directly coincided with the price spike, making traditional news the primary driver. Social media activity was not mentioned in the provided research.

Outcome: Before Jun 27, 2026

📈 June 20, 2026: 40.0pp spike

Price increased from 55.0% to 95.0%

What happened: The primary driver of the 40.0 percentage point price spike was traditional news reporting on June 20, 2026, that UK Prime Minister Keir Starmer was expected to announce a timetable for his departure, potentially as early as June 22, 2026 [2][1][6][3]. These reports indicated Starmer was reflecting on his future amidst mounting pressure from his cabinet and Labour MPs, intensified by Andy Burnham's recent by-election victory [5][7][4]. This significant breaking news directly coincided with the market movement. Social media was not a primary driver, as the provided information does not indicate any relevant activity from key figures or viral narratives.

📈 June 19, 2026: 54.0pp spike

Price increased from 0.0% to 54.0%

What happened: The primary driver of the 54.0 percentage point spike on June 19, 2026, was breaking news from traditional outlets indicating a high likelihood of Keir Starmer's impending departure. Reports confirmed by cabinet allies, including Business Secretary Peter Kyle, that Starmer was "reflecting on the political situation" [5][8] signaled a significant shift from his previous defiant position. This coincided with widespread media reports that he was considering resigning and might announce a timetable for his departure as early as Monday, June 22, 2026 [1][6][4][9]. Social media was not indicated as a primary driver or significant accelerant in the provided research.
Sources (9)
  1. 1Signs grow that Starmer will set out timetable to resign as mood in government shifts - BBC Newsbbc.co.uk
  2. 2Report says UK PM Starmer ready to quit, but source says he is still...reuters.com
  3. 3Keir Starmer expected to announce departure as prime minister on...theguardian.com
  4. 4Starmer on the brink: PM considering resigning, confirms senior cabinet minister | The Independentindependent.co.uk
  5. 5Starmer reflecting on political reality as he considers future, says allybbc.com
  6. 6Signs grow that Starmer will resign as government mood shiftsbbc.com
  7. 7Starmer is on the precipice as pressure builds for the UK leader to resign | The Independentindependent.co.uk
  8. 8PM under pressure from Labour MPs and ministers to set timetable for exitbbc.com
  9. 9Starmer expected to announce departure on Monday as growing...theguardian.com

4. Market Data

Contract Snapshot

This market resolves to YES if Keir Starmer officially announces his intention to leave or actually departs as Prime Minister of the United Kingdom before July 1, 2026. An official announcement must be reported by at least one specified source agency and cannot indicate a departure more than a year from the statement date. The market resolves to NO if these conditions are not met by June 30, 2026, 11:59 pm EDT, or if his departure is due to death or a temporary absence.

Available Contracts

Market options and current pricing

Outcome bucket Yes (price) No (price) Last trade probability
Before Oct 1, 2026 $0.97 $0.04 97%
Before Nov 1, 2026 $0.98 $0.03 98%
Before Dec 1, 2026 $0.99 $0.02 99%

Market Discussion

While market odds strongly favor Keir Starmer's departure (90-93% across various deadlines), the discussion shows some disagreement among traders. Arguments for his departure cite historical patterns where leaders facing significant electoral losses and diminishing party support tend to resign. Conversely, those betting against his departure express skepticism about the likelihood of such an event, with one trader suggesting he will "fight it all the way."

5. Who are the leading candidates to replace Keir Starmer, and what is the established process for a Labour Party leadership election?

Leading contenderAndy Burnham [1][2][3]
MP nominations for leadership81 (20% of Labour MPs) [4][5][6][7]
Starmer departure probability (prediction market)Up to 46% before July 1, 2026 [8]
Prime Minister Keir Starmer faces calls for resignation as of June 21, 2026, with speculation suggesting he might announce his departure timetable as early as Monday, June 22, 2026 [9][1][2]. This pressure is also reflected in prediction markets, where the implied probability of a Starmer departure announcement before July 1, 2026, has risen to 46% [8].
Andy Burnham leads potential candidates for leadership in the event of a contest, with Secretary West Streeting also expected to contend [1][2][3]. Burnham's recent securing of a House of Commons seat qualifies him to challenge for the leadership position [1][2].
Labour's election process requires specific member support for challengers. The established procedure mandates that a challenger must be a member of the Parliamentary Labour Party (PLP) in the Commons and secure nominations from 20% of Labour MPs, which currently stands at 81 individuals [4][5][6][7]. Should a leader in government resign, the Cabinet, in consultation with the National Executive Committee (NEC), would appoint an interim leader until a formal ballot takes place [4][7].
Sources (9)
  1. 1Signs grow that Starmer will set out timetable to resign as mood in government shifts - BBC Newsbbc.co.uk
  2. 2Starmer is on the precipice as pressure builds for the UK leader to resign | The Independentindependent.co.uk
  3. 3Daybreak Weekend: Fed Meeting, UK Election, BOJ Decision | Bloomberg Daybreak: US Editionyoutube.com
  4. 4How do Labour Party leadership contests work?instituteforgovernment.org.uk
  5. 5Leadership elections: Labour Party - The House of Commons Librarycommonslibrary.parliament.uk
  6. 6What is Andy Burnham's path to becoming Labour leader and prime minister? - BBC Newsbbc.co.uk
  7. 7What are Labour's rules for a leadership election if Keir Starmer is challenged? - LabourListlabourlist.org
  8. 8Will Keir Starmer leave office? — 45% · Kalshi | SimpleFunctionssimplefunctions.dev
  9. 9Keir Starmer expected to announce departure as prime minister on...theguardian.com

6. What evidence from public statements and factional alignments suggests Andy Burnham has the necessary support among Labour MPs to force a leadership change?

Labour MPs calling for leadership changeApproximately 100 [1][2][3]
Proposed leadership transition monthSeptember 2026 [1][4][2][3][5]
Preferred transition methodOrderly 'coronation' or managed transition [1][4][2][3][5]
Andy Burnham's by-election victory triggered calls for Starmer's resignation. Following Andy Burnham's June 2026 Makerfield by-election victory, approximately 100 Labour MPs reportedly urged Keir Starmer to step aside [1][2][3]. This indicates significant internal party pressure for a leadership change, stemming from both public and private appeals [1][2][3].
Burnham's allies advocate a smooth leadership transition, avoiding a formal contest. Supporters of Andy Burnham, alongside various Labour MPs, are advocating for a smooth 'coronation' or managed transition rather than a formal leadership contest [1][4][2][3][5]. Some suggest a handover in September 2026 [1][5]. Burnham’s appeal is notably broad and cross-factional among Labour MPs, drawing support from both the soft left (Tribune group) and some on the party's right [1][2][6]. A key challenge for Burnham, however, will be to cultivate relationships with MPs elected in 2024 [1][2][6].
Sources (6)
  1. 1Labour MPs demand Burnham ‘coronation’ as PM with ministers set to urge Starmer to quit | The Independentindependent.co.uk
  2. 2Politics Home Article | Andy Burnham Plans Meetings With Labour MPs As He Pushes For No 10politicshome.com
  3. 3Makerfield by-election: ‘Don’t delay Starmer challenge’, impatient Labour MPs urge Burnham | The Independentindependent.co.uk
  4. 4Andy Burnham gets backing from London MPs as he marches on No10 after Makerfield victory | The Standardstandard.co.uk
  5. 5Andy Burnham’s allies ‘want Starmer to hand over power in September’ | The Independentindependent.co.uk
  6. 6Who are Andy Burnham’s key allies in Westminster? | The Independentindependent.co.uk

7. How do recent polls from major firms like YouGov compare the public approval ratings and head-to-head voter preference for Keir Starmer versus Andy Burnham?

Britons viewing Burnham as better PM23-25% (head-to-head polling) [1]
Britons viewing Starmer as better PM12% (head-to-head polling) [1]
Public views neither as good PM or no differenceRoughly 50% [1]
Andy Burnham is widely preferred over Keir Starmer as Labour leader. As of June 2026, Andy Burnham is broadly considered a more favorable and preferred choice for Labour leader by both the British public and Labour members compared to Keir Starmer [2]. Head-to-head polling further indicates that significantly more Britons perceive Andy Burnham as a better potential Prime Minister than Keir Starmer [1]. This public preference for Burnham to replace Starmer has remained consistent, even amidst a recent decline in Burnham's own favourability ratings leading up to his Makerfield by-election victory [2][3].
Polling details highlight a clear preference for Burnham as Prime Minister. Approximately 23-25% of Britons view Andy Burnham as a better potential Prime Minister, while only 12% hold this opinion for Keir Starmer [1]. A substantial portion of the public, roughly 50%, believes that either neither candidate would make a good Prime Minister or that there is no perceivable difference between them [1]. Furthermore, Britons generally believe that Burnham should challenge Starmer for the Labour leadership [4], suggesting that Keir Starmer is currently facing significant political difficulties [5].
Sources (5)
  1. 1How do Britons feel about an Andy Burnham comeback?yougov.com
  2. 2Andy Burnham continues to be the public’s preferred choice to replace Keir Starmer | Ipsosipsos.com
  3. 3Andy Burnham and Wes Streeting's national favourability ratings fall...ipsos.com
  4. 4Britons tend to think Burnham should challenge Starmer for Labour leadershipyougov.com
  5. 5Wall Street Week | Britain’s Debt Problem, Poland’s Economic Boomyoutube.com

8. What political maneuvers, such as a cabinet reshuffle or a confidence vote, could Keir Starmer realistically employ to survive the current crisis?

Event triggering pressureAndy Burnham's victory in Makerfield by-election on June 21, 2026 [1][2][3]
Potential resignation announcementAs early as Monday, June 22, 2026 [1][4][3]
Ministerial adviceMany cabinet ministers advised Starmer to step down [3]
Prime Minister Starmer faces severe pressure following a by-election loss. Prime Minister Keir Starmer is confronting significant internal pressure to resign in the wake of Labour Party rival Andy Burnham's victory in the Makerfield by-election on June 21, 2026 [1][2][3]. Previously considered political maneuvers, such as a cabinet reshuffle or a confidence vote, are now largely viewed as ineffective or secondary options. This shift is attributed to Starmer's considerable loss of authority in the current crisis [3][5].
Starmer is now widely expected to announce his departure. Reports indicate that numerous cabinet ministers have advised Starmer to step down to avoid further humiliation [3]. Speculation suggests that he may announce a timetable for his departure as early as Monday, June 22, 2026 [1][4][3]. Prediction markets show high activity, with current speculation heavily favoring a near-term exit for the Prime Minister [6][7][8][9]. Additionally, Secretary West Streeting is anticipated to launch a bid for the Labour leadership if a contest occurs [10].
Sources (10)
  1. 1Signs grow that Starmer will set out timetable to resign as mood in government shifts - BBC Newsbbc.co.uk
  2. 2Starmer is on the precipice as pressure builds for the UK leader to resign | The Independentindependent.co.uk
  3. 3Talk of Starmer staying on to fight is fading fastbbc.com
  4. 4Starmer expected to announce departure on Monday as...theguardian.com
  5. 5Starmer given deadline: ‘Quit by Tuesday or face humiliation’ | The Independentindependent.co.uk
  6. 6Starmer Out by June 30, 2026? Polymarket Odds | PolySpotterpolyspotter.com
  7. 7Starmer out by...? Predictions & Odds 2026 | Polymarketpolymarket.copilot.markets
  8. 8Starmer out by...? — Prediction Markets | FRCresearchfrc.com
  9. 9Keir Starmer out before July? | Myriadmyriad.markets
  10. 10Daybreak Weekend: Fed Meeting, UK Election, BOJ Decision | Bloomberg Daybreak: US Editionyoutube.com

9. What precedents from the resignations of Theresa May and Boris Johnson indicate a likely timeline from peak crisis to a departure announcement?

Precedent crisis-to-resignation durationapproximately 48 hours [1]
Theresa May resignation dateMay 24, 2019 [1][2][3]
Boris Johnson resignation crisis startJuly 5, 2022 [4][5][6]
UK Prime Minister resignations often follow peak crises within two days. Precedents from the resignations of former UK Prime Ministers Theresa May and Boris Johnson suggest that a departure announcement after a peak political crisis could occur within approximately 48 hours. Both leaders announced their resignations around two days after an intense period of political pressure culminated, establishing a pattern for such high-stakes political departures.
Specific events illustrate this 48-hour timeline for May and Johnson. Theresa May announced her resignation on May 24, 2019, roughly 48 hours after an intense "peak crisis" phase, which followed months of cumulative political pressure and failed attempts to find cabinet and party consensus [1][2][3]. Similarly, Boris Johnson's resignation followed approximately 48 hours after a mass, coordinated wave of ministerial resignations began on July 5, 2022 [4][5][6]. The speed and volume of over 50 resignations made his position untenable within two days, despite initial defiance [4][5][7].
A similar rapid timeline may apply to current political challenges. As of June 21, 2026, prediction markets reflect extreme volatility around a potential Keir Starmer departure, with media reports suggesting an expected resignation announcement on Monday, June 22, 2026 [8]. Keir Starmer is currently experiencing significant political trouble [9], indicating a contemporary situation where similar rapid developments could unfold.
Sources (9)
  1. 1Theresa May to resign as British prime minister: Timeline of Brexit and events that led to her demise | Fox Newsfoxnews.com
  2. 2Theresa May resigns over Brexit: What happened? - BBC Newsbbc.co.uk
  3. 3She told the Queen she was off, then stepped outside to face her destiny: the inside story of Theresa May's resignationtelegraph.co.uk
  4. 4Boris Johnson: The inside story of the prime minister's downfallbbc.com
  5. 5Boris Johnson: The backstory to the PM's dramatic resignation - BBC Newsbbc.co.uk
  6. 6Timeline: 24 hours of chaos leave Boris Johnson on the brinkpolitico.eu
  7. 7Boris Johnson resigns: It is painful to leave Downing Street, says PM - BBC Newsbbc.co.uk
  8. 8Starmer Exit Bet Hits 88% On Polymarket After Monday Resignation Reportcryptoadventure.com
  9. 9Wall Street Week | Britain’s Debt Problem, Poland’s Economic Boomyoutube.com

10. What Could Change the Odds

Key Catalysts

As of June 21, 2026, UK Prime Minister Keir Starmer has not announced his departure, but reports indicate he is facing significant pressure to resign and may set out a timetable for his exit as early as Monday, June 22, 2026 [1][2][3][4][5]. Political pressure has intensified following a by-election victory by Andy Burnham in Makerfield, leading several cabinet members and MPs to urge Starmer to consider his position amid declining authority and popularity [2][3][4][5].
The political trouble surrounding Keir Starmer is a concern for bond markets [6]. Should a leadership contest take place, Secretary West Streeting is also expected to mount a bid for the Labour leadership [7].
Prediction markets are actively tracking Starmer's potential departure, with some markets indicating high probabilities for his exit within 2026. However, there is no specific verified "December 1" announcement catalyst in mainstream reporting, suggesting that date may be associated with market resolution deadlines or user-generated speculations rather than confirmed political events [8][9][10][11].

Key Dates & Catalysts

  • Expiration: May 08, 2026
  • Closes: December 01, 2026
Sources (11)
  1. 1Report says UK PM Starmer ready to quit, but source says he is still...reuters.com
  2. 2Signs grow that Starmer will set out timetable to resign as mood in government shifts - BBC Newsbbc.co.uk
  3. 3Signs grow that Starmer will resign as government mood shiftsbbc.com
  4. 4Starmer reflecting on political reality as he considers future, says allybbc.com
  5. 5Starmer is on the precipice as pressure builds for the UK leader to resign | The Independentindependent.co.uk
  6. 6Wall Street Week | Britain’s Debt Problem, Poland’s Economic Boomyoutube.com
  7. 7Daybreak Weekend: Fed Meeting, UK Election, BOJ Decision | Bloomberg Daybreak: US Editionyoutube.com
  8. 8Keir Starmer departure announced? | Prediction Markets | Coinbasecoinbase.com
  9. 9Will Keir Starmer resign in 2026? | Manifoldmanifold.markets
  10. 10Starmer out by July 31, 2026 59% Yes · Polymarketexplorer.struct.to
  11. 11Starmer out by...? Predictions & Odds 2026 - Polymarketpolymarket.com

12. Related News

+40.0pp
Last updated: June 21, 2026, 13:05 UTC

Starmer Departure Odds Surge as Burnham Win Fuels Labour Revolt

Following Andy Burnham’s decisive by-election victory, prediction markets have aggressively repriced the timeline for UK Prime Minister Keir Starmer’s departure, with contracts now implying a near-cer...
+35.0pp
Last updated: June 21, 2026, 13:05 UTC

Burnham By-Election Win Pulls Starmer Departure Odds Sharply Forward

Andy Burnham’s decisive victory in the Makerfield by-election on Friday, June 19, 2026, triggered a significant repricing in prediction markets, with traders sharply increasing the odds of Prime Minis...
-15.0pp
Last updated: June 21, 2026, 13:05 UTC

Starmer Survival Odds Lengthen as Market Prices Lower Chance of Summer Exit

In a significant repricing on Tuesday, June 02, 2026, prediction markets lowered the implied probability of U.K. Prime Minister Keir Starmer leaving office over the summer. All contracts for a departu...
-24.0pp
Last updated: June 21, 2026, 13:05 UTC

Market Lengthens Timeline on Potential Keir Starmer Exit

The prediction market for the tenure of UK Prime Minister Keir Starmer saw a significant shift on Monday, May 18, 2026, as traders lowered the probability of an imminent departure. Probabilities fell ...
+37.0pp
Last updated: June 21, 2026, 13:05 UTC

Starmer Exit Odds Surge for Summer 2026 Amid Political Crisis

The prediction market for Keir Starmer’s tenure as UK Prime Minister saw a significant repricing on Saturday, May 16, 2026, as traders sharply increased the probability of his departure within the nex...

13. Historical Resolutions

Historical Resolutions: 4 markets in this series

Outcomes: 0 resolved YES, 4 resolved NO

Recent resolutions:

  • KXLEAVESTARMER-26MAY19: NO (May 19, 2026)
  • KXLEAVESTARMER-26MAY15: NO (May 15, 2026)
  • KXLEAVESTARMER-26JUN01: NO (Jun 01, 2026)
  • KXLEAVESTARMER-26MAY01: NO (May 01, 2026)