Sir Keir Starmer’s premiership enters its most perilous phase this Thursday as British voters go to the polls in local and devolved elections that pollsters predict will deliver a historic rebuke to his Labour government. The party is forecast to lose between half and three-quarters of its 5,000 council seats in England, while in Wales – a Labour stronghold for 27 years – the latest YouGov projection places Plaid Cymru first, Reform UK second, and Labour relegated to a humiliating third. Viewed from Westminster, the scale of the expected defeat has already triggered quiet plotting among Labour MPs to demand the prime minister set a departure date.

The campaign has been unusually vicious, reflecting a broader fragmentation of British politics. Nigel Farage’s Reform UK, buoyed by Donald Trump’s return to the White House and a relentless focus on immigration, has targeted Labour’s ancestral seats in the Welsh valleys and post-industrial English towns. In Merthyr Tydfil, Farage rallied supporters with talk of a “political revolution,” while in Peterborough, a city emblematic of middle England’s discontent, voters openly express fury at Labour. “They are bastards,” one resident told a Swiss newspaper – a sentiment captured by polls showing Reform poised to win over a third of the vote in many working-class wards.

The Conservatives, meanwhile, fight merely to avoid irrelevance, squeezed between Reform on the right and the Liberal Democrats in the shires. The Green Party has emerged as a potent challenger in inner-London districts such as Lewisham, where they are projected to take 35% of the vote, pulling Labour voters leftward over climate and antisemitism concerns. The latter has become an unexpectedly central issue: a series of attacks on Jewish communities has prompted cross-party accusations, with each side blaming the other for stoking hatred.

In Scotland, the picture is equally grim for Labour. The SNP remains dominant, but the real story is the collapse of the two-party duopoly that has governed Britain for a century. Analysts in London note that if Reform and the Greens consolidate their gains, the next general election could produce a hung parliament and a period of coalition horse-trading unprecedented in modern times.

The immediate question is whether Starmer can survive. A leaked open letter from Labour MPs demanding his resignation is expected if the results are as dire as forecast. Deputy leader Lucy Powell has praised Greater Manchester mayor Andy Burnham as “incredibly popular” while insisting Starmer is “resilient,” a balancing act that underscores the knives being sharpened. For Starmer, Thursday is not merely a midterm test: it is a referendum on his leadership, and the verdict may already be written in the electorate’s disillusionment.