Prime Minister Sir Keir Starmer has told his allies that he will stand in any Labour leadership contest triggered against him, hardening his stance amid growing pressure from within the party.
Until now, Starmer and his inner circle had only insisted he would not resign if a contest were called, but stopped short of committing to fight it. However, after Greater Manchester Mayor Andy Burnham indicated he would enter a potential contest, Starmer's resolve stiffened, according to BBC sources.
The prime minister argues that a leadership battle would plunge the country into chaos, and he insists he won a landslide mandate two years ago that he is determined to deliver on.
With former Health Secretary Wes Streeting and Burnham circling—and scores of Labour MPs urging Starmer to quit—speculation about a challenge has mounted for weeks.
A key factor is the Makerfield by-election on 18 June, which Burnham must win to be eligible to stand. But Starmer's decision to fight means the prospect of a full-blown Labour leadership scrap has increased.
As the sitting leader, Starmer would automatically appear on the ballot sent to party members, should a contest be triggered.
Addressing the BBC's Any Questions programme, Burnham said: "I think Wes Streeting seems to have launched a leadership contest, so if that is running, I would seek to join it. But I'd have to persuade members of the Parliamentary Labour Party to do the same."
Streeting has confirmed he would enter any contest and has encouraged support for Burnham in Makerfield, saying he wants "a proper contest with the best candidates on the field."
Pressure on Starmer intensified after Labour suffered a historically poor set of election results last month, losing control of the Welsh Senedd and nearly 1,500 council seats in England. Streeting and several junior ministers resigned in the aftermath, while Burnham set his sights on returning to Westminster via the Makerfield by-election.