Wes Streeting walked out of Cabinet last week and the Polymarket "Starmer out by 31 December" contract -- which had been trading around 80% that morning -- sat at the low 70s by Thursday evening.

The market read Streeting’s resignation as a non-trigger event, at least regarding Starmer’s potential resignation. A contributing factor to this is that, although Streeting quit publicly, he didn’t file the 81 nominations a formal leadership challenge requires, so the market repriced accordingly.

If you have a position on this market, or are thinking about one, the coming weeks and months will present a handful of specific events that may very well shape prices on this market.

This piece is the first of several posts on this topic. We’re going to dive into what a rebellion against Starmer would actually need to do, why it hasn’t done it yet, and what signals to look for when deciding what position to take.

Well, because people have been asking him to step down.

Of course, that’s not the kind of well-informed take you’ve come to expect from OddChain, so we’re going to be a bit more specific.

Starmer won the largest Labour parliamentary majority in modern British history in July 2024, with 411 seats and a 172-seat majority. Twenty-two months later, however, his Health Secretary has resigned to challenge him, roughly ninety-five of his own MPs have publicly demanded his exit (as of May 14), the most popular Labour politician in the country has been handed a route back to Parliament, and the prediction markets price an ~80% probability he is gone before the next general election.

If you’re Starmer, this is not a good position to be in (assuming you want to keep your job).

Since 1945, eleven general elections have produced a government with a Commons majority of over 50 seats, and of those PMs, five left office mid-term.

They were:

This gives us (using 1945 as a baseline) a base rate of roughly 45%.

This suggests that a large majority has never been reliable protection from a mid-term exit, given that all five departed under internal party pressure rather than parliamentary defeat.

Although there are surely many factors that brought us to this moment, the proximate trigger we’ll begin our story with was May 7, when the United Kingdom held local council elections across England -- along with elections to the Welsh Senedd and the Scottish Parliament -- where Labour suffered what’s being described as one of the worst electoral defeats in the party’s modern history.

The Guardian, NPR, Al Jazeera, and CNN all report that Labour lost more than 1,400 council seats across England, ceded the Welsh Senedd to the pro-independence Plaid Cymru, and failed to recover ground against the Scottish National Party. Reform UK, the right-wing populist party led by Nigel Farage, gained more than 1,400 seats and is now the leading party in national voting intention polls. And, to top that all off, Starmer’s personal favorability sits at -46 net on YouGov. (Note: It’s been negative since, at least August 2024.)

Since then, the parliamentary Labour Party began to fracture. According to a running tally maintained by LabourList and corroborated by Press Association reporting picked up by CNN, close to 100 Labour MPs have publicly called either for Starmer’s immediate resignation or for him to set a timetable for departure.

On May 12 four junior ministers -- Miatta Fahnbulleh (the minister for devolution, faith and communities), Jess Phillips (the safeguarding minister), Alex Davies-Jones (the minister for victims and violence against women and girls), and Zubir Ahmed (a junior health minister and known ally of Wes Streeting) -- resigned. It was reported that six Cabinet ministers had privately urged Starmer to set a transition timetable. And by May 14, roughly 90 to 95 Labour MPs had publicly called for him to stand down.

Then Streeting walked, posting a resignation letter explicitly stating Starmer "will not lead the Labour Party into the next general election." The same day, Angela Rayner was cleared by HMRC on the tax case that had cost her the deputy premiership in September 2025, restoring her as a viable successor. And Josh Simons resigned as MP for Makerfield, with reporting confirming the seat was being cleared for Andy Burnham.

Counterweighting all of this, more than one hundred Labour MPs have signed a separate letter opposing a leadership contest, arguing that triggering one in the middle of a cost-of-living crisis would be self-destructive. Starmer himself told the cabinet meeting that he would "get on with governing" and explicitly framed any attempt to remove him as comparable to the Conservative chaos of recent years.

The crucial fact about this crisis is the gap between public dissent and the procedural step required to remove a sitting Labour leader. Labour Party rules require 81 MPs -- 20% of the parliamentary party -- to sign the nomination papers of a single named challenger. While ninety-five MPs have called for Starmer to go in the press, none have put a name on paper. And a counter-letter publicly backing Starmer has 161 signatures.

Essentially, there are three main reasons a rebellion hasn’t coalesced.