Tory leadership contender Jeremy Hunt has stepped up his warning that the party faces being destroyed in a general election unless it can deliver Brexit.
The Foreign Secretary said the Peterborough by-election, which saw the Tories finish third, showed there was “no future” for the Conservatives unless the UK’s withdrawal from the European Union was completed before a general election.
Leadership frontrunner Boris Johnson also said that a failure to deliver Brexit risked putting Labour’s Jeremy Corbyn in Number 10.
Their comments came as Theresa May was due to formally stand down as Tory leader, although she will carry on as Prime Minister and acting party leader until her successor is in place.
The Peterborough election saw the Tories slump to third place, behind victors Labour and the Brexit Party, in a seat which had traditionally been a Conservative-Labour marginal.
Tory leadership rivals warned that the result showed a general election could allow Mr Corbyn to take power.
Mr Hunt said the “incredibly disappointing” result showed there was “no future for our party until we deliver Brexit”.
“Any elections before then will just allow Corbyn to sneak through the middle,” he said.
Mr Johnson said: “Conservatives must deliver Brexit by October 31 or we risk Brexit Party votes delivering Corbyn to No 10.”
Health Secretary Matt Hancock said the result showed the “real opponent” is Mr Corbyn’s Labour, rather than the Brexit Party.
“We need to deliver Brexit then turn the page with a fresh face and concentrate on all the other things that matter to people,” he said.
Dominic Raab said failure to deliver Brexit by October 31 “would not only break our promise to voters, it risks delivering Jeremy Corbyn by the backdoor”.
The end of Mrs May’s reign as Tory leader will come in a private exchange of letters with the joint acting chairmen of the backbench 1922 Committee, Charles Walker and Dame Cheryl Gillan.
A call for candidates will then be issued at 5pm, with nominations opening at 10am on Monday and closing at 5pm the same day.
Under the timetable set out by the party high command, it is expected the new leader will be in place in the week beginning July 22, following a postal ballot of the party’s 120,000 grassroots members.
Mrs May prepares to step down amid a growing row with Chancellor Philip Hammond over her plans to leave with a series of big spending announcements, including a multibillion pound overhaul of England’s schools and colleges, according to the Financial Times.
The reported row comes after Downing Street defended the need for ambitious action to tackle climate change following warnings from the Treasury that cutting the UK’s greenhouse gas emissions to zero by 2050 will cost £1 trillion.
Even as the formalities around Mrs May’s departure were taking place, the 11 contenders so far to declare in the race to succeed her were engaged in increasingly bitter exchanges.
Former Brexit secretary Mr Raab was at the centre of a political storm after he suggested he could be prepared to suspend Parliament to prevent it blocking a no-deal Brexit on October 31.
Home Secretary Sajid Javid became the latest contender to denounce the idea, calling it “anti-democratic and anti-British”.
Mr Javid said that while he wanted to leave the EU by the cut-off date of October 31, he accepted Parliament was entitled to a say.
“I wouldn’t prorogue Parliament. That is a complete nonsense. My policy would be to do everything I can to leave the European Union on October 31,” he said.
“If it got to a point where I had to choose between no-deal or no Brexit, I would pick no-deal. But whatever I do, Parliament is going to want to have its say on it and Parliament should have its say.
“Our Parliament is sovereign. I am not into this proroguing Parliament rubbish. It is just a complete nonsense and anti-democratic and anti-British.”
Mr Javid also took a sideswipe at leadership front-runner Boris Johnson over his comments last year saying Muslim women who wear the burka looked like letter boxes.
“I think they they are wrong. I don’t think they are the right comments. I don’t think any serious politician should use language like that,” he said.
Meanwhile, Michael Gove received a boost, as Tory Party vice-chairman Kemi Badenoch announced she was quitting her post at Conservative headquarters to join his campaign.