Keir Starmer is facing a battle for Labour's soul today as Corbynites launch an all-out assault after the disastrous Hartlepool by-election.
Hard-Left figures are queuing up to warn the leader he will be 'out of a job' unless he stops 'flag-waving' and returns to more Socialist policies.
But sources close to Sir Keir insist the brutal defeat in a constituency the party has held for nearly 50 years, together with early evidence of a dire showing in English councils, demonstrate the need to 'accelerate the programme of change'.
Modernisers have also lashed back by complaining that the party is still suffering from 'Long Corbyn', in a grim reference to coronavirus.
Former Cabinet minister Lord Mandelson listed the results of decades of general elections in a striking interview on BBC Radio 4's Today - pointing out that Tony Blair's three victories were the only positive outcomes since the 1970s.
Diane Abbott, shadow home secretary under Mr Corbyn, tweeted: 'Crushing defeat for Labour in Hartlepool.'
MP for Brighton Kemptown Lloyd Russell-Moyle took to Twitter to question his party's attempts to change its image
Richard Burgon, who was shadow justice secretary under Jeremy Corbyn, said the party 'urgently' needed to 'change direction'
Labour is facing a disastrous Super Thursday in a blow to Sir Keir Starmer's (pictured today) bid to rebuild after the losses the party suffered in 2019
As sources from across the political spectrum reacted to a dire night for Labour, a host of left-wingers attacked Sir Keir.
Diane Abbott, shadow home secretary under Mr Corbyn, tweeted: 'Crushing defeat for Labour in Hartlepool.
'Not possible to blame Jeremy Corbyn for this result. Labour won the seat twice under his leadership. Keir Starmer must think again about his strategy.'
Richard Burgon, who was shadow justice secretary under Jeremy Corbyn, said the party 'urgently' needed to 'change direction'.
'Incredibly disappointing defeat in Hartlepool. We are going backwards in areas we need to be winning,' he said.
'Labour's leadership needs to urgently change direction. It should start by championing the popular policies in our recent manifestos – backed by a large majority of voters.'
Former shadow chancellor John McDonnell told BBC Radio 4's Today programme: 'Keir's got to be given his chance and I've said that all the way along.
'I'm not going to be one of those people treating (him) the way they treated Jeremy (Corbyn) – always challenging him, coups and all the rest.
'Keir now needs to sit down and think through what happened in this campaign, and what I've been saying to him is you need to demonstrate to people the sort of society you want to create, the policy programme that will achieve that society, and you need to get back to that real grassroots campaign.
'We must never again send our candidates into an election campaign almost naked, without a policy programme, without a clear view on what sort of society you want to create.
'That's the sort of thing that we need now.'
The Corbnite grassroots group Momentum described the Hartlepool by-election result as a 'disaster'.
Co-chair Andrew Scattergood said: 'A transformative socialist message has won in Hartlepool before, and it would have won again.
'Starmer's strategy of isolating the left and replacing meaningful policy with empty buzzwords has comprehensively failed.
'If he doesn't change direction, not only will he be out of a job – but the Labour Party may be out of government forever.'
MP for Brighton Kemptown Lloyd Russell-Moyle took to Twitter to question his party's attempts to change its image.
He said: 'Good to see valueless flag waving and suit wearing working so well... or not?'
The comment was a clear reference to a leaked strategy document which suggested Labour must make 'use of the flag, veterans, dressing smartly' to win back voters in red wall seats in the party's former industrial heartlands.
He added later: 'If Keir wants to be a 'British Biden' he should learn from USA Democrats, where policies united the party, the left was brought into top table not pilloried, reforming polices are presented as common sense and Uncle Joe speaks for woke liberals and blue collar left at same time.'
Labour MP for Brighton Kemptown Lloyd Russell-Moyle has publicly mocked his party's election strategy
Lord Peter Mandelson, a former Labour MP for Hartlepool, said he feels 'fairly gutted' at the result in Hartlepool and also 'a mild fury'.
'I feel sad, disappointment above all, for the excellent campaign workers and party staff and volunteers and our excellent candidate, Paul Williams, who fought such a strong campaign,' he said.
He added: 'I also feel, I have to say, a mild fury, that the last 10 years of what we have been doing in the Labour Party nationally and locally has brought us to this result, because that is above all fundamentally an explanation of what's happened today.'
Lord Mandelson went on: 'What I would say is this, and remind the party we have not won a general election in 16 years.
'We have lost the last four, with 2019 a catastrophe – the last 11 general elections read: lose, lose, lose, lose, Blair, Blair, Blair, lose, lose, lose, lose.
'We need for once in this party to learn the lessons of those victories as well as those defeats, and I hope very much that when Keir and his colleagues in the shadow cabinet say this means that we have got to change direction that they actually mean it.'
Lord Mandelson insisted that Brexit had not been raised with him once on the doorstep.
'The one thing they did raise with me however is Jeremy Corbyn – he is still casting a very dark cloud over Labour. Labour voters are not letting this off lightly, he still gets them going on the doorstep,' he said.
'One person said to me 'Sort yourselves out, sort yourselves out. You picked the wrong brother and you ended up with Corbyn so that's goodbye to you. When you've sorted yourselves out, we'll look at you again'.
Shadow minister Steve Reed was sent out to shore up Sir Keir's position, insisting the party was getting a better reception on doorsteps.
Speaking on BBC Breakfast he said: 'We're going to see a lot more results throughout today and Saturday and over the weekend, from elections right across the country, so we'll have a clearer picture at the end of that period, and I suspect the results are going to be patchy.
'Certainly from my door-knocking – places like Sheffield, Nottingham, Bristol, Milton Keynes, Hertfordshire – the reaction on the doorstep to me as a Labour campaigner has been a lot warmer than it has been in recent years, but that isn't enough if it's not translating into votes.
'So I think people understand the leader has changed, they don't understand the party has changed, because we haven't yet done enough to prove that.'
Mr Russell-Moyle was an ally of Mr Corbyn before joining the shadow frontbench under Sir Keir.
He stepped down as the shadow minister for air quality and the natural environment last July.
His resignation came weeks after he apologised to author JK Rowling for writing an article where he accused her of 'using her own sexual assault as justification for discriminating' against trans people.
In 2018, he hit headlines after he was suspended from the Commons for picking up the ceremonial mace in protest at a Brexit vote being deferred.
Lloyd Russell-Moyle reacted furiously after the Government whip formally postponed the vote - because then-PM Theresa May was facing a humiliating defeat.
The mace is the symbol of the authority of the House and during sittings is placed on the table next to the despatch box in front of the Speaker.
In 2019, Russell-Moyle joined thirteen other Labour MPs on Westminster Bridge, next to the Houses of Parliament, in a protest against Brexit under the banner 'Love Socialism Hate Brexit'.
Counting is now underway in the Hartlepool by-election as the Tories try to win the seat from Labour
The Labour Party has held Hartlepool since the constituency's inception back in the 1970s