Andy Burnham says he will challenge Keir Starmer for the Labour leadership, despite holding back from saying he would trigger a contest.The Greater Manchester Mayor, widely seen as the main rival to Mr Starmer, said a vote for him in Makerfield would be a vote to “change Labour”, but has not explicitly said he would launch a bid until now.His statement, during a BBC Question Time by-election special, drew criticism from the Prime Minister. Mr Starmer's spokesperson said the Prime Minister would not walk away from his mandate and the country wanted the Labour Party to focus on governing, not internal debates.While Mr Burnham’s intention to become prime minister this summer is no secret, his statement is the first time he has explicitly said he would seek to enter a contest to replace Mr Starmer. It sets up the prospect that the UK could have another change of leader within months, if Mr Burnham becomes eligible to challenge for the premiership by winning the Makerfield by-election on June 18.He said a “fundamental change” was needed in Westminster to restore the public’s trust in politicians.“If I get your support, I would seek to represent you at the highest possible level and give this constituency maximum power and influence,” Mr Burnham said.He cited the ambitions of his top rival, former health secretary Wes Streeting, in explaining his plans to seek leadership of his party. “I think Wes Streeting seems to have launched a leadership contest, so if that is running, I would seek to join it,” he said. “But I’d have to persuade members of the Parliamentary Labour Party to do the same.“So that’s the only question… I’ve said to my team, let’s have a proper look at this and let’s develop a policy.”A poster for Labour candidate Andy Burnham in the window of a home in Bryn, west of Manchester, ahead of the Makerfield by-election. AFPInfoMr Starmer’s government is teetering on the verge of collapse, less than two years after his landslide general election victory in July 2024. He has become the least popular prime minister since reliable public opinion polling in the wake of a series of scandals and policy missteps, as well as criticism from his own members of Parliament that he doesn’t have a plan to deliver the change he promised voters.That sentiment was confirmed at a set of local elections last month in which the governing Labour party suffered heavy losses, generating calls from more than 90 Labour MPs for Mr Starmer’s resignation.Mr Streeting resigned his Cabinet post, saying it would be “dishonourable and unprincipled” for him to stay on after he told the Prime Minister that he had lost confidence in his leadership. However, he held back from attempting to trigger a leadership contest, with polling suggesting he would lose in a head-to-head battle with his former boss.Mr Burnham then put himself forward to run in the vacated Makerfield seat, a precursor to a leadership bid. He has ruled out calling a snap election if he enters Downing Street, a spokesperson said in response to speculation the former cabinet minister was considering such a move to give him a stronger mandate.Mr Burnham is one of 14 candidates standing in the election, which was triggered when Labour’s Josh Simons stood down.The vote is expected to be a race between Mr Burnham and Reform UK’s candidate Robert Kenyon, a plumber and local councillor.A by-election poll released on Thursday evening showed Mr Burnham with 49 per cent of the vote, ahead of Mr Kenyon on 39 per cent.The Survation poll, which had a sample size of 518, put Rebecca Shepherd of Restore Britain on 8 per cent and Sarah Wakefield of the Green Party on 2 per cent, with the Lib Dems and Conservatives on 1 per cent.Britain's Prime Minister Keir Starmer, left, visits a construction site in York, northern England on Thursday. AFPInfoMr Burnham also used his Question Time appearance to criticise the rhetoric of Reform UK leader Nigel Farage over the murder of a white British teenager, which has become national news because of the police’s handling of the case. He said Mr Farage’s decision to publish a video on social media calling for Britons to react to the case with “rage” had “consequences” in the form of unrest and violence against the police.“The ringleaders of that violence used exactly the same words as the leader of the Reform Party when they were orchestrating that violence,” Mr Burnham said.“Honestly, do we want to carry on as Britain down this path towards a politics like the United States of America, where if people vote different ways, they won’t talk to each other and they won’t have any relationship with each other?”