Starmer pledges to go on - if he falls, who could replace him?

British Prime Minister Keir Starmer refused on Monday to heed calls to quit, even by the leader of his party in Scotland, pledging to fight on after his appointment of Peter Mandelson as US ambassador plunged his government into crisis.

Under pressure over the appointment of a man whose close ties to the late US sex offender Jeffrey Epstein have come into full focus, Starmer has attempted to change the narrative.

But a demand from Anas Sarwar, leader of the Scottish Labour Party, for him to quit and the departure of a second senior aide in as many days did little to stop the questions over his judgment and ability to govern.

The resignation of communications chief Tim Allan followed the exit of Starmer's closest aide, Morgan McSweeney, who said he took responsibility for advising on the appointment of Mandelson to Britain's top diplomatic role in the United States.

Despite Sarwar's intervention, Starmer later received messages of support from his top ministers and some potential leadership rivals, and a positive reception at a meeting of Labour Party lawmakers suggested there would be no imminent move to oust him.

"After having fought so hard for the chance to change our country, I'm not prepared to walk away from my mandate and my responsibility to my country, or to plunge us into chaos, as others have done," Starmer told the meeting, saying his focus was preventing the populist Reform Party, headed by veteran Brexit supporter Nigel Farage, from taking power.

"That is my fight, that is all of our fight, and we're in this together."

Febrile mood

With his statement, Sarwar became the most senior Labour figure to call for Starmer's resignation, and did little to quell a febrile mood in parliament in London's Westminster.

With Starmer losing his fourth director of communications, his record in government is under scrutiny, including the gaffes and policy U-turns that have tainted his almost two years in power.

"It's painful," said one Labour lawmaker on condition of anonymity. "It's like watching a fatal car crash in slow motion."

But Starmer received a show of support from his deputy, David Lammy, finance minister Rachel Reeves and foreign minister Yvette Cooper, among others. Angela Rayner, his former deputy who is seen as a leading leadership candidate, offered him her "full support".

He was greeted with a round of applause from the Labour members of parliament, and one lawmaker who was at the meeting said: "he is safe for now."

With McSweeney's departure on Sunday, Starmer had hoped to reset the narrative and attempt to return to an agenda he has so far failed to keep any focus on - tackling the cost-of-living crisis and boosting the British economy.

The leader of the opposition Conservative Party, Kemi Badenoch, accused Starmer of being unable to run his government.

"He's like a plastic bag blowing in the wind. We need him to get a grip and if he can't do it then someone else in the Labour Party needs to do that, or they should have an election," she told Sky News.

Two huge pitfalls await Starmer as he seeks to regain control. On February 26, voters go to the polls in the Gorton and Denton by-election, a vote caused by the resignation of Labour MP Andrew Gwynne on medical grounds. 

Gwynne won the seat at the 2024 general election with a majority of 13,000 votes having secured more than half of the vote. Labour is being challenged strongly by insurgents on both the left in The Green Party and on the right in Reform and could finish in third place.

Such a result would lead to huge soul-searching among Labour MPs, particularly after Starmer blocked Manchester Mayor Andy Burnham from standing in the contest. Burnham was regarded as having planned to launch his return to parliament in a bid to challenge Starmer for the leadership. 

Local elections in May, in which Labour faces a terrible set of results, could be the final straw for Starner's colleagues. 

Runners and riders

In that event, which Labour politician might take over as Prime Minister ?

Angela Rayner, former Deputy Prime Minister, is popular. But she awaits the results of an investigation into her tax affairs. 

Health Secretary Wes Streeting is second favorite, although his perceived closeness to Mandelson might finish his chances.

Interior Minister Secretary Shabana Mahmood has impressed, but her tough immigration stance repels soft left MPs. 

Ed Miliband was leader when Labour lost the 2015 election. He's popular among party members. 

Foreign Secretary Yvette Cooper also has supporters. 

Veteran Defense Secretary John Healey, an MP for 29 years, is seen as a safe pair of hands, possibly in a caretaker capacity.

Andy Burnham is Labour's most popular politician, but in the light of Starmer's recent refusal to let him stand for parliament again he's out of the running.