Keir Starmer's 'make or break' fightback speech appeared to have failed last night amid an avalanche of calls for him to quit.

The embattled Prime Minister tried to head off a coup by warning that it would plunge Britain into 'chaos'.

But the intervention looked to have flopped yesterday as the long list of Labour MPs calling for him to consider his position grew to more than 70 last night.

In a speech to party activists, Sir Keir insisted he would not 'walk away' even if he faced a leadership challenge this week.

He warned that a contest now would risk 'plunging our country into chaos, as the Tories did time and again – chaos that did lasting damage to this country'.

Labour, he said, would 'never be forgiven for inflicting that on our country again'.

But Labour critics of the Prime Minister said the speech had failed to win them over.

Maverick backbencher Catherine West said the speech was 'too little, too late'.

Ms West dropped a threat to launch an immediate leadership challenge, but urged MPs to sign a letter calling for the PM to set out a timetable to step down.

Last week's local elections disaster saw Labour lose 1,500 councillors and 38 councils in England and trail in third place in Wales and Scotland. Labour MPs reported that voters vented their anger at Sir Keir personally, with one saying he was 'detested on the doorstep'.

The PM acknowledged that voters were 'frustrated' with him, but insisted he could win them round.

'I know that people are frustrated by the state of Britain, frustrated by politics – and some people – frustrated with me.

'I know I have my doubters and I know I need to prove them wrong – and I will.'

Culture Secretary Lisa Nandy, who was sent out on the airwaves to defend the PM, said he was right to 'acknowledge mistakes he made' and the personal animosity towards him.

But asked if he had done enough to save his skin, she told Sky News: 'No, it's not enough, to go out and make a speech, but it is certainly the right thing to have done in this moment – to go out and acknowledge the mistakes that have been made, to acknowledge, the role that he's personally played in that.'

Sir Keir set out a smattering of new measures including legislation to nationalise British Steel, a ban on 'far-Right agitators' coming to the UK for a planned march on Saturday and a plan to put the UK 'at the heart of Europe'.

But he stopped short of unveiling the kind of radical change many Labour MPs had been demanding – and suggested it would be a mistake to change direction in the wake of 'tough' election results.

He cast the current political moment as a 'battle for the soul' of the UK, warning that if Labour failed, the country would head down 'a very dark path'.

Sir Keir said: 'This is nothing less than a battle for the soul of our nation and I want to be crystal clear about how we will win it because we cannot win as a weaker version of Reform or the Greens.

'We can only win as a stronger version of Labour, a mainstream party of power, not protest.'

Sir Keir said Nigel Farage and Zack Polanski lacked 'the serious progressive leadership these times demand'. Mr Farage, he said, was 'not just a grifter, he is a chancer' who had led the country into a failed Brexit.

The PM said the Government would take 'a big leap forward' towards the European Union, but struggled to explain what this would mean in practice.

Until now Sir Keir has stuck to Labour's 2024 election pledge that the UK would not rejoin the single market or customs union, or return to free movement. But asked if he was ruling out the party's next manifesto campaigning to go back into the European Union, he failed to do so.

Instead, he replied: 'What I want to do is take a big leap forward with the EU-UK summit this year and take us closer, both on trade, the economy, defence and security. And that will then be a platform on which we can build as we go forward.'

His spokesman later added that the so-called red lines on Brexit apply only until the general election and that 'the next manifesto is a matter for the party'. 

In his speech Sir Keir also claimed that Brexit 'snatched away' young people's ability to work, study and live in Europe as he pledged to agree an 'ambitious' youth experience scheme with Brussels.

Afterwards leading pro-EU Labour MP Stella Creasy urged him to rip up his red lines on Brexit, saying: 'They need to go now and be seen to go now otherwise it's a waste of time.'

But others warned it would only see more Red Wall voters peel away to Reform, with influential Labour peer Lord Glasman saying: 'It's the estrangement of working-class voters from Labour that is absolutely not going to be resolved by a speech realigning with the EU. I can't imagine anything worse.'

A handful of backbenchers spoke up in support of the Prime Minister in the immediate aftermath of the speech, with Macclesfield MP Tim Roca and Gedling's Michael Payne saying Sir Keir had demonstrated he understood 'the scale of the challenge' facing the country.

But many others continued to call for his resignation.

North Northumberland MP David Smith, who has been the UK's special envoy for freedom of religion or belief since 2024, said Labour owed 'a debt of gratitude' to Sir Keir but could not 'carry on with the approach we have taken' since the General Election.