The Tory party could be wiped out unless Brexit happens on October 31, Boris Johnson warned his fellow MPs as he set out his pitch to be the next prime minister.
The leadership frontrunner promised that he could deliver Brexit and avoid the “potential extinction” of the Conservatives.
His stark warning was echoed by fellow Brexiteer Andrea Leadsom, who said a delay to the UK’s exit from the European Union could “spell the end” for the party.
Their comments, at a private hustings for MPs organised by the One Nation group of centre-right Conservatives, came as hardline Brexiteers demanded that the next prime minister signs up to the October 31 deadline.
A paper published by the European Research Group called on leadership contenders to abandon Theresa May’s Withdrawal Agreement and the Political Declaration setting out the future UK-EU relationship and step up preparations for a no-deal exit on World Trade Organisation terms.
At the first major hustings of the leadership contest, more than 80 MPs packed into a Commons committee room to hear from Mr Johnson, Mrs Leadsom, Sajid Javid and Rory Stewart.
The former foreign secretary, who was described as being in a “subdued” mood with a “serious” tone, promised that he could take on Nigel Farage’s Brexit Party and Jeremy Corbyn’s Labour – although he ruled out a snap election.
“We need to realise the depth of the problems we face – unless we get on and do this thing (Brexit), we will be punished for a very long time,” he said.
“There is a very real choice between getting Brexit done and the potential extinction of this great party – but I believe I can take on Farage and win back the voters being won over by him.”
Ex-Cabinet minister Nicky Morgan, one of the leading figures in the One Nation group which organised the event, said Mr Johnson told MPs if Brexit was delayed again there was a risk the “relevance” of the 2016 referendum result “starts to wane”.
Asked about Mr Johnson’s warning about the future of the party, Mrs Morgan said: “I think we all know that the stakes are very high.”
Home Secretary Mr Javid stressed the party should not seek to emulate the Brexit Party and ruled out a pact with them.
In a comment met with appreciative banging of desks, he said: “We will not beat the Brexit Party by becoming the Brexit Party.”
International Development Secretary Mr Stewart told the event: “I began this race believing I should be a truth-teller on principle – ironically I have discovered that it is very popular – and the only way to avoid an election and win the next one is by being straight with people.
“No more unicorns, no more red lines, no more promises we can’t deliver. That’s how we get Brexit done, defeat Corbyn and unify the country”
The influential ERG will set out its latest blueprint for Brexit on Wednesday.
Deputy chairman Steve Baker said: “The Withdrawal Agreement and the Political Declaration have failed absolutely. They are not coming back.
“The next leader of the Conservative Party needs to know that and act on that basis.
“Our new prime minister will have three months to get this right, or that’s it – for this government, this parliament and this party.”
The ERG paper has the support of 16 Tories, including the group’s chairman Jacob Rees-Mogg and former Conservative leader Iain Duncan Smith.
Both Kit Malthouse and James Cleverly pulled out of the leadership race ahead of the party setting out new rules to speed up the contest, which now has 11 contenders.
Candidates now need to secure support from eight MPs rather than the two required under the system used in 2016.
To stay in the contest, candidates will then need to win more than 16 votes in the first ballot and 32 in the second round in order to speed up the process of whittling them down to a final two.
The first ballot of MPs will take place on June 13, with further votes scheduled on June 18, 19 and 20.
The winner – and the next prime minister – will be decided by Tory members from the two candidates remaining at the end of the process by the week beginning July 22.