Labour promised voters they wouldn't do this. Yet here they are, on the verge of giving the UK its seventh prime minister in a decade. Talk of Sir Keir Starmer fighting to stay is fading fast as the weekend wears on, with the PM holed up at Chequers with his wife, while Andy Burnham, the man coming for his job, enjoys family time away from home.

The reasons for Labour to switch leader are compelling. Burnham looks like a winner: he's beaten Reform, a party that until now seemed a deadly threat to Labour, and he's genuinely popular - a rare trait among politicians. Swathes of MPs are eager to back him, believing he can fix the party's grim position. "He's an instinctive guy - that's his great talent," said one source. As Mayor of Greater Manchester, he's known simply as "Andy" everywhere, and he's no stranger to government, having served as health secretary, culture secretary, and Treasury minister. Most importantly, Burnham showed in the Makerfield by-election campaign that he has the rare talent of making people feel good - something Labour in Westminster has apparently forgotten how to do.

Starmer's government has been a mess of more than a dozen big U-turns, resignations, and the Lord Mandelson job fiasco. After dreadful election results in 2025 and 2026 and a wipe-out in Wales, he seems like a loser to many in his own party. It's not even two years since his massive general election win, but the perception that he appeals to voters? Brutally, that's long gone.

On Friday, Starmer was still insisting to cameras he'd fight if challenged, refusing to acknowledge that it's not an "if" but a "when." Privately, some backers insisted he'd run, citing donors who've funded a campaign and office spaces being found. One source claimed cabinet conversations weren't about whether he had authority to stay but what arguments he'd make in a leadership race. Several sources told me Starmer really believes he could beat Burnham, concluding this after watching him on BBC's Question Time and then failing to explain borrowing rules on Newsnight. A government insider said: "On Saturday he phoned his closest allies and said, 'I'm sure I could win'."

But the widespread assumption is that Burnham would win hands down. Another source called it "nuts" to imagine the PM could come out on top. Increasingly, even loyal ministers think it's time - one cabinet source said they "wouldn't want the prime minister to humiliate himself" in a race. The chances of him staying are diminishing, but how Starmer will respond remains a mystery. "It's very hard for people to know a person who doesn't know themselves," said a government insider.

Don't underestimate the anger towards Burnham inside Downing Street, shared by some ministers. It's not just about what's happening now but how they see he's chipped in unhelpfully from the sidelines since Starmer moved into No 10. One Starmer ally told me: "This is not a chase, these are big decisions about who is going to run the country - it can't be rushed 20 minutes after a by-election."

Many in Labour aren't sure what Burnham would actually do in office. Former minister Jess Philips said he must be "tested with the rigour of at least some manner of contest." Minister Mike Tapp bluntly told me he'd never met him and "I don't know his politics." A backer of the PM claimed Burnham "fell apart" under tough questions in the by-election campaign. There's also concern about ousting a leader based on a by-election of only 77,000 voters deciding for the whole country. Burnham would have no public mandate without a general election.

What if Labour's standing didn't improve? Would the removal vans come again? Could other big names from the past - David Miliband or Ed Balls - abandon New York and the breakfast TV sofa for a comeback? The risks are serious. With 100 MPs now calling for Starmer to go, one senior figure predicts "he'll realise this weekend that he can't keep the Cabinet and ministers together and will have to go."

Labour has found itself in a strange situation it promised it would never reach - on the verge of removing the leader who delivered its first general election victory in 19 years, congratulating themselves for holding a seat they already had so they can dump the man who won them all their seats. Whether Starmer goes willingly or is forced out, one veteran figure sums it up: "It's done."