Jeremy Corbyn is on course to be prime minister as Conservative support plummets, according to an analysis of recent polling.

Labour could capitalise on the Brexit delay to sweep into power, with the Tories set to lose 59 seats in the event of a general election, according to Electoral Calculus research for The Sunday Telegraph.

The analysis is the latest in a clutch of surveys which point to a collapse in the Conservative vote, with two other polls this weekend putting support for the party at its lowest in at least five years.

The Electoral Calculus poll of polls carried out between 2 and 11 April indicated Labour would become the largest party in the Commons, with 296 seats against the Conservatives’ 259.

Leave-supporting Tory voters would be drawn towards Ukip or Nigel Farage’s Brexit Party after Theresa May failed to deliver on her vow to take the UK out of the EU on 29 March, the research suggests.

Former Conservative leader Iain Duncan Smith and Amber Rudd, the work and pensions secretary, are among the MPs at risk of being voted out, according to the polls of 8,561 people.

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“The Conservatives’ failure so far to secure Britain’s withdrawal from the European Union is at risk of costing them dearly,” said Sir John Curtice, president of the British Polling Council.

Writing in the Telegraph, he added: “[It] would not be enough to give Jeremy Corbyn a Commons majority – but it could be enough to propel him into Downing Street if he could secure the support of the SNP in a parliament that would be even more badly hung than the current chamber.”

Mr Duncan Smith called on Ms May to stand down as soon as next month, describing the party’s failure to leave the EU on time “a disaster”.

“The big problem was as soon as we didn’t leave you could see all the poll ratings start to crash,” he told Sky’s Sophy Ridge On Sunday.

Martin Baxter, founder of Electoral Calculus, said: “Theresa May is discovering why David Cameron really held the referendum. It wasn’t to placate his own Eurosceptic MPs; instead it was to stop Conservative voters defecting to pro-Brexit parties. That process seems to have restarted and the Conservatives are beginning to suffer.”

A separate poll by Opinium put Labour seven points ahead of the Tories.

Conservative support dropped six points in a fortnight to stand at 29 per cent – the party’s worst performance in the survey since 2014. The poll put Jeremy Corbyn’s party on 36 per cent, up one point from 29 March.

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The research echoed the findings of YouGov polling which this week found Tory support had slumped to its lowest level in six years. The survey for The Times put Theresa May’s party on 28 per cent in the event of a general election, down four points since the start of April, with only a two-thirds of Tory voters in the 2017 saying they would back them again.

Labour were on 32 per cent, up one point. The Lib Dems were on 11 per cent, with Ukip in 6 per cent and the Brexit Party on 8 per cent.

Mr Corbyn’s ability to form a government in the event of a hung parliament would be likely to depend on the support of the SNP, who could demand a second EU referendum as a bargaining chip.