Leading pollsters say the "Burnham bounce" – the surge in Labour support after Andy Burnham replaced Sir Keir Starmer as prime minister on 20 July – has already fizzled out, with the party making no further gains and even slipping behind Reform UK in some surveys. This matters because it undermines any suggestion that Labour could benefit from calling an early general election to secure Mr Burnham a personal mandate, with experts saying there is no rational basis for doing so. It comes as Mr Burnham prepares to face MPs for the first time since taking office, under pressure to set out policies beyond his early summer giveaways ahead of a difficult October Budget.

Sir John Curtice said the bounce ended after roughly two weeks, with Labour's August lead over Reform averaging no more than one point, while Lord Robert Hayward suggested some of the boost may reflect declining support for Nigel Farage and Green leader Zack Polanski rather than genuine enthusiasm for Burnham. Polls from 17-23 August showed Labour static or falling in five of six surveys, with figures ranging from a Politico poll putting both parties level on 23 per cent to a BMG poll giving Labour a four-point lead; Labour's support sits in the mid-20s, well below its 32 per cent share at the 2024 election.