The government has made a fresh plea to MPs get behind Theresa May’s Brexit deal in Tuesday’s crucial Commons vote.
A group of MPs are understood to be planning to take control of the Brexit process if, as widely expected, Mrs May’s deal is voted down.
And Labour leader Jeremy Corbyn has vowed to table a vote of no confidence in the government if she loses, which could trigger a general election.
The PM has warned of “catastrophic” breach of trust if Brexit is thwarted.
Writing in the Sunday Express, Mrs May said failing to back her deal could lead to a no-deal Brexit or no Brexit.
Brexit Secretary Stephen Barclay told the BBC’s Andrew Marr show: “There are lots of different plans being put forward by Members of Parliament that don’t respect the result or risk no deal.”
Pressed on what happens if the deal is defeated, Mr Barclay said he suspected the Commons would support something “along the lines of this deal” but declined to speculate on whether the government had a Brexit “plan B” lined up.
Mr Corbyn said Labour would vote against Mrs May’s deal and if she lost would start moves to trigger a general election.
He told the Andrew Marr show: “We will table a motion of no confidence in the government at a time of our choosing, but it’s going to be soon, don’t worry about it.”
The Labour leader has said his party does not have the votes in Parliament to win a confidence vote on its own and has appealed to other parties to support it.
Northern Ireland’s DUP party, which keeps Mrs May in power, is also planning to vote against her deal but has said it will support Mrs May in a confidence vote.
Mr Corbyn is facing growing calls from within his own party to back a second EU referendum.
He told Andrew Marr he hoped to get a general election first, before saying: “My own view is that I’d rather get a negotiated deal now, if we can, to stop the danger of a no-deal exit from the EU on 29 March – which would be catastrophic for industry, catastrophic for trade and the long-term effects of that would be huge.”
He was repeatedly asked whether Labour would campaign to leave the EU if a general election was called, but sidestepped the question.
The Labour leader said his party would “decide our manifesto content as soon as we know there’s an election coming”.
He said he would have to ask the EU to extend Article 50, the legal process taking the UK out of the EU on 29 March, if he won an election, so he could go to Brussels to negotiate a different Brexit deal, which would see the UK being part of a customs union.
“Clearly if Theresa May’s deal is voted down, clearly if a general election takes place and a Labour government comes in – an election would take place February, March time – clearly there’s only a few weeks between that and the leave date, there would have to be time for those negotiations.”
The UK will leave the EU on 29 March unless there is a new act of Parliament preventing that.
Because the government controls the timetable for Commons business, it was assumed that this would not be possible.
But a group of MPs, including former Tory ministers, are reported by the Sunday Times to be working on a way to allow non-government members to take control of the timetable and bring forward legislation making it illegal to leave the EU without a deal, if Mrs May loses Tuesday’s vote.
Dominic Grieve, who has been at the forefront of cross-party efforts to ensure MPs have a say in what happens if Mrs May’s deal is voted down, told the BBC that reports that he was plotting with Commons speaker John Bercow were “rubbish”.
Mr Grieve, a former attorney general, told the BBC he did meet Mr Bercow on Tuesday but they had not been plotting last Wednesday’s events, when Mr Bercow broke with precedent to allow a vote on Mr Grieve’s amendment that led to a government defeat.
How could MPs take over Brexit?
Currently, the government has precedence in the House of Commons. It controls how and when business, including legislation, is organised.
However, some backbenchers are seeking to wrest that control away from them.
If MPs can get an amendment to change how and when Commons business is arranged passed by a majority, backbench business could then take precedence over government business.
This could represent a threat not just to Brexit legislation but to the government’s ability to govern, says Downing Street.
It would mean that without control over time in the Commons, the government has no control over parliamentary business, so cannot get through policies and legislation easily.
In terms of Brexit, it means MPs could block a no-deal by making it a legally binding requirement for government to stop Brexit on 29 March.
On Monday the debate on the meaningful vote on Mrs May’s deal will resume for a fourth day.
The vote had been scheduled to take place in December but was called off at the last minute by the prime minister, who was facing almost certain defeat.
Last week the government was defeated twice in the Commons on Brexit votes.
While in the second they voted for the government to come back to the Commons with a plan B for Brexit within three days should it lose Tuesday’s vote.
More than 100 Conservatives and 10 DUP MPs are among those set to oppose the government’s deal on Tuesday.
Labour is also set to vote against the deal, but leader Jeremy Corbyn has resisted growing calls from within his own party to get behind another EU referendum, insisting a general election is still his top priority if the deal is rejected.
Need some guidance?
If you feel like you ought to know more about Brexit…