Tories brand Rishi Sunak 'the worst PM ever' saying he caused the party's catastrophic meltdown by 'knifing' Boris Johnson - and warning he '100%' must go if exit poll is borne out

The Tories were already descending into bitter recriminations tonight after the bombshell exit poll showed them heading for meltdown.

Senior Conservatives immediately demanded Rishi Sunak quits after the extraordinary figures emerged on the close of polls.

A former Cabinet minister - who regards their own significant majority as under threat said Mr Sunak had 'knifed' Boris Johnson and would be remembered as the 'worst PM ever'. 

Another veteran Conservative said Mr Sunak '100 per cent' has to go, even though the result was better than some had feared. 'The question is whether they appoint a new leader before party conference (in September) or after,' they added.    

The extraordinary exit poll showed Sir Keir winning 410 of the 650 seats. That would be a majority of 170 - just short of the 179 achieved by Tony Blair.

The Tories are expected to be slashed from the 365 secured less than five years ago to just 131 - their worst performance in modern political history. 

Meanwhile, the Lib Dems could get 61 - and Nigel Farage's Reform insurgents are predicted to have 13 after effectively leeching millions of votes from the Conservatives. 

That could include Mr Farage himself taking Clacton, while Conservative sources in Great Yarmouth confirmed they expected Reform to triumph there. 

However, polling guru Sir John Curtice warned that the numbers for Reform were highly uncertain. 

Mr Sunak gave a deadbat response, merely praising activists. 'To the hundreds of Conservative candidates, thousands of volunteers and millions of voters: Thank you for your hard work, thank you for your support, and thank you for your vote,' he posted on X. 

A Tory spokeswoman insisted that they would wait for the full results to emerge. 

Although the exit survey, run for broadcasters by Sir John, is not guaranteed to be exact, it has accurately reflected the outcome in the past few elections.

The SNP would be slashed to 10, meaning they would no longer be the biggest party in Scotland. 

Sir Keir gave a muted reaction to the bombshell, posting on social media: 'To everyone who has campaigned for Labour in this election, to everyone who voted for us and put their trust in our changed Labour Party - thank you.' 

But his allies were far less restrained, with Lord Mandelson gloating that he was 'gobsmacked' and an 'electoral meteor' had 'struck planet Earth'. He said it would have required a 'superman' to save the Tories and Rishi Sunak 'is not superman'.

Deputy Labour leader Angela Rayner - who could be set to become deputy PM within hours - said the numbers were 'encouraging' and praised Sir Keir's leadership. 

Shadow health secretary Wes Streeting was in tears as he was told the figures on live TV. 

A dire campaign for Mr Sunak came stuttering to a halt last night, with the PM making a series more defensive visits in the South East.

He now faces the prospect that he could be out of Downing Street by tomorrow morning, if the results pan out as badly as anticipated in the coming hours.

Former Scottish Conservative leader Ruth Davidson told Sky News that it looked like a 'massacre'. 

A host of big beasts including Chancellor Jeremy Hunt in Goldaming & Ash and Grant Shapps in Welwyn Hatfield will now be waiting nervously to see if they fall victim to the Labour and Lib Dem onslaught. There are fears those with the highest majorities could end up most vulnerable, with Home Secretary James Cleverly and even ex-PM Liz Truss thought to be at risk. 

The Tories could quickly plunge into a dangerous new phase of crisis, with questions over whether it can even survive amid the challenge from Reform. 

Former home secretary Suella Braverman has already waded into the shadow leadership contest, penning an article on the eve of the election blaming the failure to tackle immigration.  

Sir John Curtice told the BBC: 'It looks as though Reform may win more seats than many polls suggested.

'This is largely because, not only has the Conservative vote fallen far in seats they previously held, but also because Reform has advanced most in areas people voted Leave in the 2016 EU referendum.

'However, how many seats Reform will win is highly uncertain – our model suggests there are many places where they have some - but a relatively low - chance of winning.'

Conservatives with big majorities had become increasingly nervous during the day, despite CCHQ claiming that higher-than-expected turnout could help them.