Candidates clashed over Brexit escape routes during the BBC Tory leadership debate.
With four of the five candidates willing to accept a no-deal Brexit, Rory Stewart was the only one to rule it out entirely.
Insisting it would not be possible to negotiate a new deal by October 31, Mr Stewart said the existing Withdrawal Agreement was the only way out of the EU.
Flagging up how all the candidates had voted for Theresa May's deal, he called on them to do so again, saying "let's get on with it, let's vote it through, let's get it done".
Ruling out no-deal Brexit entirely, he said: "In the end we're in a room with a door, and the door is called Parliament, and I am the only person here trying to find the key to the door.
"Everybody else is staring at the wall shouting 'Believe in Britain'."
But Michael Gove said MPs could not just be presented with the same "cold porridge" of Mrs May's deal for a fourth time.
He said: "We've run into that door three times already, Rory – we've got to have a different route out.
"You cannot simply re-present the same cold porridge for a fourth time and ask people to say that's what they want.
"We need to have a different approach."
Frontrunner Boris Johnson claimed that leaving on October 31 was "eminently feasible", agreeing with Sajid Javid that there must be a deadline.
But Jeremy Hunt and Mr Gove both stressed how the date was arbitrary and getting a deal was more important than sticking rigidly to a date – although Mr Gove stressed he would guarantee leaving the EU before the end of 2019.
In response to a question about the Irish backstop, Mr Javid said he could solve the border issue using "existing technology" – although BBC presenter Emily Maitlis pointed out that the existence of the technology to do so is in doubt.
He said: "It is perfectly possible to have an open border with two different customs arrangements on either side of the border using existing technology.
"Obviously it will take time to put that in place, it will cost money."
Mr Johnson also said the issue could be solved during the implementation period.
"You can solve the questions of how to keep goods flowing freely across that border whilst the UK comes out of the EU.
"You can solve that issue during the implementation period whilst we negotiate the free trade deal."