The options for Brexit "are narrowing", Health Secretary Matt Hancock has said, after MPs voted to seize control of the parliamentary timetable, reports BBC.
The PM was dealt a fresh blow as the government was defeated by 27 votes on Monday, on a plan designed to find out the kind of deal MPs would support.
Thirty Conservative MPs rebelled, including three ministers.
Mr Hancock said the government would listen to MPs but "can't pre-commit to following whatever they vote for".
He told Radio 4's Today programme that the Commons had rejected no deal and a second referendum, and urged MPs to back the PM's Brexit deal.
Richard Harrington, Alistair Burt and Steve Brine resigned to join the rebels, with Mr Harrington accusing the government of "playing roulette with the lives and livelihoods" of Britons.
On Monday night, MPs voted in favour of Conservative backbencher Sir Oliver Letwin's cross-party amendment, which will allow MPs to put forward motions relating to Brexit - most likely a series of so-called indicative votes.
Because of this, MPs will be able to vote on a number of options on Wednesday - likely to include a "softer Brexit", a customs union with the EU and another referendum - designed to test the will of Parliament to see what, if anything, commands a majority.
The prime minister said she was "sceptical" about the process - as it was not guaranteed to produce a majority for any one course of action - and she would not commit the government to abiding by the result.
"The votes could lead to an outcome that is un-negotiable with the EU," she told MPs.
Mr Hancock told Today: "In the previous votes there have been a multitude of potential different options - the sorts of options, like a second referendum, which I think would be a bad idea, that's been rejected.
"The idea of having a no deal…the Commons is absolutely clear it won't allow and will legislate against it if necessary.