Allies of the prime minister are making it clear he would fight any challenge to his leadership from Labour MPs.

There are fears from those loyal to Sir Keir Starmer that his job might be under immediate threat, perhaps as soon as shortly after the Budget in a fortnight's time.

Critics say it is evidence that Downing Street is "in full bunker mode" which "won't help the government out of the hole we're in."

Friends of Sir Keir are deeply worried about what they see as plotting going on to try to replace him and are seeking to make clear what they see as the grave risks of a leadership challenge.

Those names being discussed by Labour MPs as potential candidates to displace Sir Keir include some of his closest cabinet allies, especially Wes Streeting, the health secretary, and Home Secretary Shabana Mahmood.

Some also speculate about the ambitions of Ed Miliband, the energy secretary, and backbenchers including the former transport secretary Louise Haigh.

The ambition of Streeting is seen with particular suspicion from some loyal to the prime minister.

Speaking to BBC Breakfast, Streeting called suggestions he would challenge Sir Keir "self-defeating nonsense", and said he was not standing against the prime minister.

Asked if he would ever consider making such a move, he replied: "I cannot see circumstances under which I would do that to our prime minister."

He said the prime minister should sack the aide who was responsible for the briefing, which he described as "the worst attack on a faithful since Joe Marler was banished in The Traitors final".

He added that there was a "toxic culture" in Downing Street that needed to change.

One minister said: "He [the prime minister] will fight this," before making reference to a key by-election in 2021 which Labour lost to the Conservatives, prompting Sir Keir to consider resigning as Labour's leader.

"This is not a Hartlepool moment," they added.

"He is one of only two people alive who have won a general election for Labour. It'd be madness to run against him after 17 months."

Opinion polls suggest Sir Keir is deeply unpopular, perhaps even the most unpopular British prime minister in the history of modern opinion polling.

Polls also suggest the Labour Party has commanded the support of no more than a fifth of the electorate in recent months.

But, a move to replace Sir Keir isn't straightforward. Under Labour's rules, it would take 20% of its MPs to nominate a challenger - 81 given the current size of the parliamentary party in the Commons.

For months now, plenty in the Labour Party have acknowledged that the government faces a likely crunch point after devolved elections in Scotland and Wales and local elections in many parts of England next May.

Labour is widely expected to do badly in those elections, but there are growing concerns from some in the party that it can't wait until then to contemplate a change of leader.

Downing Street is aware of the potential imminence of such a threat to them.

One senior Labour MP told us: "It's all very well to say wait for the locals, but that's my activist base I'm sending into the gunfire. I can't lose all my councillors."

Another Labour source said: "The list of reasons for people to move after the Budget are growing by the day.

"If Wes is brave and moves he may well be rewarded by being prime minister by Christmas."

A government source said Downing Street "has gone into full bunker mode, turning on their most loyal cabinet members for absolutely no reason".

"Unfortunately there is a pattern of Keir's team briefing against his own people - they did it to Angela, Lisa, Lucy, now it's Wes's turn," the source added.

"A circular firing squad won't help the government out of the hole we're in," a government source said - referring to the former and current deputy leaders, Angela Rayner and Lucy Powell respectively, and the Culture Secretary Lisa Nandy.

Labour peer Maurice Glasman told BBC Two's Newsnight he couldn't see any candidate who could possibly challenge Sir Keir, saying the leadership chatter was "just noise".

"There isn't a clear direction, there isn't a clear strategy... none of the candidates challenging Keir have any idea either," he said.

When asked if Mahmood would be up to the task of addressing the issues facing Labour, Lord Glasman said: "For me, absolutely. I mean, she's the only one of really genuine quality of the whole lot, but she's got a job to do."

He added that he fully supports the prime minister and was not in favour of any challenge to his leadership.

The prime minister's supporters are telling Labour MPs they should be careful what they wish for.

They argue a leadership contest would plunge the party into the chaos associated with the final years of the Conservative Party's stint in office which came to an end last year, and install a leader who does not have their own mandate from the country.

They are trying to convince their colleagues that a contest could destabilise the international markets too, and would jeopardise the good relationship the prime minister has established with President Trump.

But others, including some ministers, fret about what they perceive to be the desperate position the government is in.

"It's terrible. He [Starmer] is hated out there. It is worse than it got under Corbyn. I don't see how this is sustainable until May," one minister said.

A cabinet minister who is supportive of the prime minister sums up the mood among their colleagues as they see it: "There are those who see it as a choice between this Labour government and perfection.

"The closer they can nudge us towards the policies they see as perfect, the happier they are.

"But the choice isn't between us and perfection, it's between us and Reform."

The rise of Reform UK has concentrated minds in Downing Street in recent months.

The prime minister sees Labour's battle with Reform leader Nigel Farage as generation-defining ? and the prospect of losing to Reform at a general election as vastly worse than Labour losses to the Conservatives.

He believes he has the energy and wherewithal to take on and defeat Farage.

But a growing number of his colleagues are not convinced.

"We are not like the Tories. We're not going to change leader more than once in a parliament," one Labour MP first elected last year told us. (BBC)

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