Keir Starmer announced his resignation as UK Prime Minister on June 22, 2026, after Labour’s heavy losses in the May local elections and growing internal party pressure. Andy Burnham’s decisive victory in the June 18 Makerfield by-election returned him to Parliament and positioned him as the clear frontrunner in the impending Labour leadership contest. Traders price Burnham highest because the governing party’s internal rules and parliamentary arithmetic favor a swift transition to a candidate who already holds a seat and commands broad support among MPs. The process, which begins with nominations around July 9 and aims to conclude before the September parliamentary session, will lead to the new leader being formally appointed by the King. Other potential contenders trail significantly, as none currently match Burnham’s near-term path to the premiership.