Starmer out by December 31, 2026?

Prediction markets put the probability at 94%: Starmer out by December 31, 2026. Currently, markets see this as likely (94% YES). Andy Burnham's election to parliament sets up bid to oust UK PM Starmer.

What’s Happening

Andy Burnham, the Greater Manchester mayor, won the Makerfield by-election on June 18, 2026, returning to parliament after a 16-year absence and immediately setting up a leadership challenge against Prime Minister Keir Starmer. The seat, vacated by the resignation of Labour MP John Simons, drew national attention as a proxy vote on Starmer's faltering premiership. Burnham, who had openly positioned the race as a launchpad for a bid to oust the prime minister, used his victory speech at The Edge Wigan to signal his intent to seek the Labour leadership, accelerating internal party manoeuvring that could see Starmer out before parliament's autumn recess. [Reuters, Jun 19]

Speaking on the sidelines of the G7 summit in Thonon-les-Bains, France on June 17, Starmer publicly warned colleagues that a leadership challenge "would be bad for Britain," after multiple Labour MPs urged him to consider his position. The intervention followed weeks of caucus discussions over the timing of any contest, with party rules requiring 20% of MPs to nominate a challenger before a formal vote can proceed. Whip-office soundings reported around the G7 indicated growing willingness among soft-left and Manchester-aligned MPs to back Burnham, while Starmer allies pushed for a confidence motion ahead of conference season to force opponents into the open. [Reuters, Jun 17]

The pressure has built against a backdrop of stalled domestic legislation and a sweeping social media ban for under-16s announced June 15, which restricted TikTok, Snapchat, Instagram, gaming and livestreaming platforms in one of the world's broadest online crackdowns. Reporting around the by-election showed Labour trailing Reform UK across multiple constituencies, with the Makerfield result widely read as confirmation that grassroots support has shifted decisively. With Burnham now seated as Makerfield MP, the next procedural milestone is the September Labour conference, where nomination filings open and a formal vote on the leadership would determine whether Starmer out scenarios materialise before year-end. [AP, Jun 19]

Traded on Polymarket — $3.2M Volume

Active market on Polymarket with $3.2M in total volume. Sufficient liquidity for most position sizes. Currently priced at 94c YES.