Trader consensus on Polymarket favors no new UK Prime Minister in 2026 at 36.5%, reflecting Keir Starmer's repeated vows to "stay the course" despite Labour's plummeting polls and backlash from a March 11 release of files showing he overruled reputational risk warnings on appointing Peter Mandelson, prompting union calls for resignation. Angela Rayner leads potential successors at 23.5% after her March 18 speech decrying the government's failure to deliver change and labeling immigration plans "un-British," reigniting speculation of an internal Labour challenge. Ed Miliband at 10% and Nigel Farage at 8.5% gain from positioning as interim or opposition alternatives amid Reform UK's surge, with May local elections poised as a pivotal test that could trigger a leadership contest or snap election under party rules allowing contests post-September conference.