Brexiteer cabinet minister Liam Fox has accused pro-Remain MPs of trying to "steal Brexit", amid backbench moves to take control of the process.
"You've got a Leave population and a Remain Parliament. Parliament has not got the right to hijack the Brexit process."
There are various backbench moves to prevent the UK leaving the European Union without a deal on 29 March.
Labour's Sir Keir Starmer said the PM should rule out a no-deal Brexit.
He said he believed it was "inevitable" that Article 50 will be delayed and that events in Parliament last week - when MPs heavily rejected the withdrawal deal Theresa May has negotiated with the EU - mean that another referendum is now more likely.
He told the BBC the prime minister must also change her "red lines" adding: "If she won't, it's difficult to see where we go from here."
On Monday, Theresa May will make a statement to MPs setting out how she intends to proceed with Brexit, amid apparent deadlock in Parliament over a way forward.
She will also table a motion to be debated and voted on, on 29 January. It is expected that various MPs will try to amend that motion over the course of the next week to put forward proposals to test the will of the Commons.