A Government health minister has suggested he could resign to vote against a no-deal Brexit next week.
Stephen Hammond said he would be "clear where my responsibilities lie" if a series of votes on February 14 turn out to be the last opportunity to block withdrawal from the EU without an agreement.
Mr Hammond was a vocal backbench opponent of a hard Brexit until he was appointed to the Government in November.
Prime Minister Theresa May is due to report back to the Commons on February 13 on progress in Brexit negotiations, setting the scene for MPs to table a series of amendments in the hope of securing a parliamentary majority on the way forward the following day.
Among proposals expected to be tabled are a repeat of the cross-party plan, drawn up by Labour's Yvette Cooper and Tory Nick Boles and defeated by 23 votes last week, which would extend the negotiation process as late as the end of 2019 to avoid a cliff-edge departure without a deal.
Asked if he would resign to back a similar amendment next week, Mr Hammond told The House magazine: "We will all have to look into our conscience at that stage. But I don't think anyone can doubt my principles and what my view would be if that is the last opportunity.
"I'm pretty clear where my responsibilities lie, much as I love this job, much as I think the NHS is a wonderful, wonderful institution.
"I'm also very clear that as Members of Parliament we have a moral duty to our country and our constituencies. If you look at my record over the last year, no one can question my moral view on that."
Mr Hammond said he remained "hopeful" that the Prime Minister would be able to secure a deal with Brussels.
Brexit: Leave and Remain supporters gather in London on 29 January
But he said that, if she had not reached that point by next week, the votes on February 14 would offer "the opportunity to ensure that no deal doesn't happen by mistake".
He said: "I have no doubt that many of my colleagues and I will take that opportunity if that appears to be the eventuality."
The Wimbledon MP, who campaigned for Remain in the 2016 referendum, said he accepted the result of the vote, but believed a no-deal Brexit would be "a catastrophe for the country".
