Tory leadership hopeful Jeremy Hunt has refused to commit to taking Britain out of the European Union before Christmas, saying prime ministers should "only make promises they know they can deliver".
The Foreign Secretary insisted it was possible to get a revised deal with Brussels by the end of September, and said if it took "a few extra days" to get it through Parliament he would delay Brexit beyond the October 31 deadline.
But, when pressed during an interview with the BBC's Andrew Neil, he refused to say whether the UK would have left by Christmas, though claimed "it's not going to be months".
Mr Hunt has said that he believes he would be able to get a new deal with Brussels, but if that proved impossible, he would prepare for no deal on October 31, making a judgment on the best course to follow at the end of September.
He expressed his confidence in getting a deal by the end of September, telling the BBC: "I believe we can and I, as I say, I think that people like Angela Merkel want to solve this problem.
"If we have a deal, if it's clear to us and to the Europeans there's a deal to be done, then of course I would go for that and if it took a little bit – you know, a few extra days – to get it through Parliament."
He said Parliament would be "willing to sit at weekends, will be willing to sit late, to do this" but that it "may take a few extra days and I would be willing to allow those days".
Asked whether he would be prepared to delay by days, weeks or months, Mr Hunt replied: "Well it's not going to be months."
But pressed on whether the UK would be out by Christmas, he said: "I'm not going to give you those commitments...
"It's because prime ministers should only make promises they know they can deliver. And there's another reason why we have to be careful about this 31st of October date.
"It is because Parliament may try and take a no deal Brexit off the table altogether and so I think – my commitment is that I think I'm the best person to get a deal and if we get a deal it will be on or around the 31st of October but I can't control what Parliament does and that's why I'm being honest with people about the difficulties."
Mr Hunt went on to say he expected Brexit to happen before Christmas and, when asked if there was any chance the UK could still go in to 2020 as a member of the EU, he replied: "I don't believe so, no."
In a swipe at his rival Boris Johnson, Mr Hunt said he would deliver Brexit "more quickly than the alternative".
"If you want to leave the EU quickly, if you want to avoid a general election, which is the risk if you go about this in the wrong way, I'm the person who has the biggest chance of negotiating that deal and getting us out by October 31."