Sir Keir Starmer insisted he is “not going to walk away” after Andy Burnham vowed to challenge his leadership. In a five-word comment, the embattled Prime Minister warned that a contest to replace him would “plunge the country into chaos”.

His comments came after the Greater Manchester Mayor stated publicly for the first time that he would launch a bid to replace Sir Keir if he wins the Makerfield by-election. Speaking during a visit to a defence contractor in Wiltshire, the PM told LBC: “I’ve said over and over again, I’m not going to walk away.

“We won an election victory in 2024 with a five-year mandate. We’re only two years into that and so I’m not going to walk away from that. I’m very clear about that.

“Andy’s got a lot of talent, of course he has. We’re fighting hard in Makerfield, but I also profoundly believe that to plunge our country into the chaos of a leadership fight, when, as we’re talking about this morning, we’re facing a war on two fronts.

“The Ukraine war is going on, we’ve got conflict in the Middle East. Both of these have to be resolved … We have to step up on defence and security of our country.

“I have already said we live in the most dangerous and volatile world in our lifetimes and that’s why I sincerely and profoundly believe that we should be getting on with the job that we were elected to do in 2024, which is taking the decisions that are priority decisions for our country, not plunging into an internal fight in the Labour Party, which will distract us from the job that we are elected to do.”

Deputy Prime Minister David Lammy had earlier warned that Sir Keir would fight any attempt to oust him.

Mr Lammy said: “There is no contest at the moment, and my view is it would be a huge distraction at this time.

“The Prime Minister, by the way, has been absolutely clear: if there is a contest, he’ll be in it.”

Mr Burnham confirmed his Labour leadership ambitions during an appearance on a BBC Question Time special for the Makerfield by-election.

He had previously promised a vote for him in the crunch ballot would be a vote to “change Labour” but had not explicitly said he would mount a bid.

Mr Burnham said: “I’m not somebody who gets ahead of myself. I can’t do anything unless I’m lucky enough to get the support of people here.

“But if I get your support, I would seek to represent you at the highest possible level and give this constituency maximum power and influence.

“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.

“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.”

It comes as new polling suggests the Greater Manchester Mayor is on course for a return to Westminster.

The Survation poll of 518 Makerfield voters gave the Labour politician a 10-point lead with 49%, while Reform UK’s local plumber candidate Robert Kenyon is second with 39%.

Rupert Lowe’s Restore Britain party is third on 8%, while the Greens take 2% and the Lib Dems and Tories 1%.

The Makerfield by-election was triggered after Labour’s Josh Simons stood down to pave the way for Mr Burnham to run.