Labour's heavy losses in early May 2026 local elections have intensified pressure on Prime Minister Keir Starmer, whose approval ratings have hit historic lows amid policy backlash and internal rebellion, fueling trader consensus that Andy Burnham leads at 42% implied probability to become the next UK Prime Minister in 2026. The Greater Manchester Mayor is advancing plans for a swift by-election return to Westminster, backed by allies including Angela Rayner—who warned of Labour's "last chance" and endorsed his comeback—positioning him as a popular northern alternative outside the Westminster bubble. A 26.5% chance of no leadership change reflects Starmer's resistance, while Rayner's 11.5% reflects her vocal criticisms, with upcoming by-election timing and potential NEC approval as key catalysts.