The government has made a fresh plea to MPs to 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 a “catastrophic” breach of trust if Brexit is thwarted.
Writing in the Sunday Express, Mrs May told MPs: “It is time to forget the games and do what is right for our country.”
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 (of the referendum) 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.
If a majority of MPs back a no confidence motion, the government – or anyone else who can command a majority – will get 14 days to try to win another confidence vote. If no-one can’t do that, a general election will be held.
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 – and ensure that the UK did not leave without a deal.
“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.”
Asked whether Labour would campaign to leave the EU if a general election was called, Mr Corbyn 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.
Downing Street has said it is “extremely concerned” about the reported plot, which it says could potentially overturn centuries of Parliamentary precedent.
Conservative MP 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.
The SNP’s leader at Westminster, Ian Blackford, said MPs must now take control of the Brexit process from the government to prevent a no-deal scenario.
He told the BBC’s Sunday Politics programme: “The prime minister’s got to stop threatening Parliament and indeed, threatening the whole of the United Kingdom, that it’s a choice between her deal and no deal – that’s not the case.
“There are other options that are open to us and Parliament has to make sure that it takes the necessary action to protect the interests of all of us.”
Lib Dem leader Sir Vince Cable, who like Mr Blackford backs another EU referendum, said: “I think Parliament will take control of this process, will insist that we pursue the option of no Brexit.”
Sir Vince said this could happen by cancelling Article 50 – which he noted would be “resented by lots of people” – or via a second referendum.
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.
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