Mounting pressure on Prime Minister Keir Starmer from poor local election results and internal Labour dissent has elevated prospects for a 2026 leadership contest, positioning Greater Manchester Mayor Andy Burnham as the frontrunner. His approval to contest the Makerfield by-election, expected within weeks, clears a key barrier to returning to Parliament and mounting a challenge, bolstered by strong public polling and member support. Recent developments include Health Secretary Wes Streeting’s resignation over lost confidence in Starmer and Angela Rayner’s clearance on prior tax matters, which could enable her candidacy. Traders assign Burnham the highest implied probability for assuming the role this year, while the notable share for no change reflects Starmer’s incumbency and the uncertain timeline for any contest or snap election.