Keir Starmer looks to have bought himself a stay of execution tonight despite fury at the Mandelson scandal and claims Angela Rayner is readying a bid for Labour's top job.

An alleged campaign website for the former deputy PM has surfaced as Sir Keir faces a mounting crisis over his future.

Scottish Labour leader Anas Sarwar delivered a shattering blow this afternoon by insisting the premier must go after the Mandelson scandal.

Mr Sarwar - who had already told Sir Keir to stay away from Scotland's local elections because he is politically toxic - said he was a 'decent man' but there had been 'too many mistakes'.

The PM immediately dismissed the attack, with a Downing Street spokesman saying: 'Keir Starmer is one of only four Labour leaders ever to have won a general election.

'He has a clear five-year mandate from the British people to deliver change, and that is what he will do.'

After more than a day maintaining an extraordinary silence over Sir Keir's woes, the Cabinet finally mobilised to prop up the embattled premier minutes before Mr Sarwar broke cover. Markets had been showing increasing signs of jitters at the prospect of turmoil at the top of Government, with no obvious successor ready to take over. 

Ms Rayner has also spoken out to offer 'full support' for Sir Keir, despite swirling rumours about her ambitions.

However, the Guardian highlighted that an angelaforleader.co.uk domain briefly went live last month. A spokesman for the Labour MP said: 'This fake website has nothing to with Angela. It was not commissioned by her or with her knowledge. She will take legal advice given the use of her name and image without her consent.' 

Allies described it as 'dirty tricks' and a 'false flag' operation. Ms Rayner is regarded as the most likely successor should a vacancy arise at the top, but has yet to resolve the situation with HMRC over that unpaid stamp duty bill that forced her resignation in September.  

The PM - who has now lost four communications directors in just 18 months - has been holed up in Downing Street all day. 

He will, however, address MPs at a meeting of the Parliamentary Labour Party at 6pm.  

Trying to quell speculation Sir Keir could simply walk away from his premiership earlier, the PM's spokesman insisted he is 'upbeat and confident' and 'concentrating on the job in hand'.

As UK politics plunges into turmoil again today:

• The interest rate on 10-year gilts - a main way the Government borrows money - has risen sharply as investors fear chaos; 
• Cabinet Secretary Chris Wormald and national security adviser Jonathan Powell remain under intense pressure over the Mandelson appointment;
• Police have yet to sign off release of documents about Mandelson's vetting process, to the frustration of Downing Street; 
• The Intelligence and Security Committee is due to meet the Cabinet Secretary tomorrow for initial talks on the Mandelson documents; 
• Sir Keir is scrambling for a new chief of staff after McSweeney's exit, with claims his biographer Tom Baldwin has been angling for the job.

Just before Mr Sarwar's press conference a host of big beasts including David Lammy, Rachel Reeves and Steve Reed finally took to social media to voice 'support' for Sir Keir. 

One senior party source said colleagues had been 'waiting to make their move' - amid chatter about a resignation that could finish the PM off. Ms Rayner, who has yet to speak out, looks to be in pole position to take over should he be ousted.

But although the whole Cabinet has now lined up behind Sir Keir, some ministers - including potential challenger Wes Streeting - appeared to stop short of giving total endorsements.

Sir Keir told his remaining Downing Street staff this morning that he was determined to 'go forward' after comms chief Tim Allan said he was 'standing down to allow a new No10 team to be built'. 

The former Tony Blair adviser had only been in the post since September. He had pledged to help Sir Keir 'turn the corner' with a reset but senior Labour sources accused him of being 'completely useless' and 'embarrassing'.

The announcement followed the departure of chief of staff Morgan McSweeney yesterday over the appointment of Mandelson as US ambassador. 

No10 revealed that Sir Keir told staff: 'We must prove that politics can be a force for good. I believe it can. I believe it is. We go forward from here. We go with confidence as we continue changing the country.' 

MPs are warning Sir Keir he must show he 'gets' the crisis and is ready to lurch to the Left when he addresses a highly-charged meeting of the Parliamentary Party this evening. 

Mr Allan said he 'wished the PM and his team every success'. But he was blamed overnight for sparking expectations that Sir Keir would give an 'address to the nation' today - something that was seemingly never planned. 

There was a notable absence of Cabinet figures rallying round the PM this morning, despite both Foreign Secretary Yvette Cooper and Darren Jones being pictured in Westminster. 

Deputy PM Mr Lammy had not spoken since Mr McSweeney's resignation, amid claims at the weekend that he warned against making Mandelson US ambassador.  

Baroness Jacqui Smith, a relatively junior minister, was put up for broadcast interviews. 

One Cabinet aide said their minister would not be posting a supportive message on social media because they 'had work to do'. 

But just before Mr Sarwar was due to start speaking ministers began posting on X. 

The Chancellor said: 'Rebuilding Britain takes time. But thanks to the decisions we've made NHS waiting lists are falling. Inflation is falling. Interest rates are falling.

'The conditions for the economy to grow are there.

'With Keir as our Prime Minister we are turning the country around.'

Mr Streeting told Sky News that 'Keir Starmer doesn't need to resign' while acknowledging it 'has not been the best week for the Government'.

In lukewarm comments he said MPs should 'give Keir a chance'. 

Ed Miliband said: 'Keir has earned the right to deliver the change he has promised and do what he cares about - which is to serve the country. 

'This is not the time for the Government to turn inwards on itself. We must focus on delivering the change we promised the country.' 

At 3.37pm Ms Rayner posted: 'I urge all my colleagues to come together, remember our values and put them into practice as a team. The Prime Minister has my full support in leading us to that end.' 

Labour sources said Work and Pensions Secretary Pat McFadden was 'f***ed over' yesterday when he was sent out on TV to defend Mr McSweeney hours before he resigned. 

But he spoke up for the premier earlier today when grilled during a visit: 'I think the Prime Minister acted in good faith throughout this. Of course he'll take responsibility for the decision to appoint Peter Mandelson in the first place, he's already done that,' he said. 

'But I think the Prime Minister is just 18 months into a five-year mandate and I support him in continuing the work he's doing for the country.'

Asked whether Sir Keir was the best person to lead the country, Mr McFadden said: 'Yes, he is.'

Challenged whether he would still be PM this time next year the minister said: 'Yes, I believe he will.'

Bizarrely a British Airways flight simulator had been installed outside No10 this morning, sparking jokes that the PM might be looking for a getaway. 

Skills minister Baroness Smith was sent out to put the PM's case on broadcast, insisting he is not on the verge of quitting. However, she conceded that she had not even spoken to Sir Keir personally.

Yesterday Mr McSweeney said he took 'full responsibility' for the decision to send the disgraced peer to Washington, despite knowing he had stood by Jeffrey Epstein after the depraved financier was jailed for child-sex offences.

Downing Street said the PM and Mr McSweeney had jointly decided it was the 'right moment' for him to go.  

Sir Keir has the advantage that rivals including Angela Rayner, Wes Streeting and Andy Burnham do not appear to be in position to challenge for the leadership.

Ms Rayner has also previously insisted an election must be called when governing parties switch leaders mid-term.

No10 has been circulating messages to normally-loyal MPs pleading for them to speak up in support of the leader at the PLP session this evening. 

But many are openly speculating about how long Sir Keir can continue without the man who masterminded his rise to power and who was seen as 'the PM's brain'.

Sir Keir previously considered quitting as Opposition leader after Labour lost the Hartlepool by-election, at the height of Boris Johnson's popularity. 

Lady Smith rejected the idea that Sir Keir is thinking of resigning, saying he is 'determined' to continue with his agenda for change.

She told Times Radio: 'No, I think that the Prime Minister absolutely is determined to. He's determined and has taken responsibility for the mistakes made in appointing Peter Mandelson.

'He's apologised to Epstein's victims, and he's determined now to put right a system that enabled this to happen.'

She insisted Sir Keir is taking responsibility when put to her that Mr McSweeney was the one taking responsibility.

'The Prime Minister is taking responsibility. He took responsibility for the decision that was made about Peter Mandelson, although, to be clear here it was, of course, Peter Mandelson that in consistent lying and engagement with Jeffrey Epstein let down the party and the Government and the country.

'And I think that will become clearer as the information around the appointment is put out into the public domain.'

Mr McSweeney's deputies, Vidhya Alakeson and Jill Cuthbertson, have been appointed joint acting chiefs of staff.

Some insiders expect that the 'smart and capable' pair will be made permanent.

However, Mr Baldwin - a former comms chief to Mr Miliband known to be close to the PM - is also said to be in the frame. One Labour veteran said that Sir Keir was 'weirdly in thrall' to Mr Baldwin.

Another option to stabilise the ship could be Baroness Louise Casey, although she is already tasked with the grooming gangs inquiry and a review of social care funding. 

Meanwhile, frantic work is continuing on the documents about Mandelson's vetting and ties to senior Labour figures.

Sir Keir was forced to commit to releasing a swathe of material last week following a revolt by MPs last week. He has insisted that the details can show that he was misled by Mandelson during the process, and there was a failure in the process.

But Scotland Yard has raised concerns about publishing information when there is a criminal inquiry ongoing. 

Sir Keir's allies are gloomy about the chances of police giving approval today, with one gloomily fearing that when they do give approval it will come at 'the worst moment'. 

Left-wingers are calling for the PM to resign, with former campaigns chief Jon Trickett warning: 'The buck stops at the top.'

Brian Leishman, the Labour MP for Alloa and Grangemouth, added: 'There must be a change in political direction and that comes from the very top.

'So the Prime Minister must look at his own position and question whether he should follow McSweeney's lead one last time, and resign for the good of the country and the Labour Party.'

Liverpool MP Kim Johnson said the PM's position was 'untenable', while York MP Rachael Maskell described Mr McSweeney's departure as 'a start'.

Ms Maskell told BBC Radio 4's Westminster Hour: 'If he hasn't understood the seriousness of the situation, then I think he will find it very difficult to continue.'

Other Labour MPs on the left of the party, including Brian Leishman, Ian Byrne and Kim Johnson, suggested Sir Keir should consider following Mr McSweeney out the door.

Two Cabinet ministers told The Times Sir Keir was 'weaker' and 'could stand down at any moment' - although No10 said that was 'categorically untrue'.

Union chiefs also heaped pressure on the Labour leader, with Fire Brigades Union general secretary Steve Wright saying he should resign.

Maryam Eslamdoust, the general secretary of the Labour-affiliated Transport Salaried Staffs' Association, told The Telegraph: 'There's no case for waiting until May, given the scale of defeat we are facing at these critical elections. It's time to elect a new leader.'

But Starmer ally John Slinger said, 'The last thing the country needs is leadership speculations,' while Labour grandee Lord Blunkett warned against 'a party acting like ferrets in a sack'.

Tory leader Kemi Badenoch said Sir Keir Starmer is allowing former chief of staff Mr McSweeney to 'carry the can' for a decision he chose to make.

She told BBC Radio 4's Today programme: '(Claiming) "I was badly advised" is not a good excuse for a leader. Advisers advise, leaders decide. He made a bad decision, he should take responsibility for that… this man said that he was the chief prosecutor for the country, when did he start believing everything that people told him?

'Peter Mandelson had been sacked twice for unethical behaviour. He is allowing someone else to carry the can for a decision that he chose to make. But the real problem is that this country is not being governed.'

She added: 'Keir Starmer promised a Government that would be whiter than white. His position now is untenable, because if he thinks that bad advice is enough for Morgan McSweeney to go, then, yes, I think that makes his position untenable.'