Theresa May could be forced into a softer Brexit or a second referendum under fresh cross-party plans for parliament to seize control of the process next week.
A new amendment - tabled by Labour veterans Hilary Benn and Yvette Cooper and Tories Sir Oliver Letwin and Nick Boles - proposes a series of ‘indicative votes’ on alternatives to the prime minister’s own UK-EU divorce deal.
If passed, it could build a Commons majority around a closer relationship with the European Union based on a customs union and single market access for trade.
In a desperate bid to head off the amendment, Cabinet minister David Lidington announced that if the PM’s deal is not passed next week, then the government would itself allow two weeks for a series of votes on alternatives.
Lidington pledged to “provide a process by which the House could form a majority on how to take things forward”.
The Benn amendment puts even further pressure on May to get her own deal approved by the Commons after a third attempt, which is expected early next week.
The PM is desperate to seek MPs back a short delay to Brexit, putting back the date from March 29 to June 30 to allow one final go at winning round her DUP partners and backbench Tory Brexiteers.
The DUP will meet ministers for talks on Monday and a ‘third meaningful vote’ on May’s deal is expected either on Tuesday or Wednesday.
Some government insiders believe that if May’s plan is approved, the Commons and Lords will be forced into sitting on Saturdays in a desperate attempt to get legislation processed.
But if the DUP and some Tory MPs refuse to budge, the new Benn amendment opens up the chance of a major shift in the whole process.
And with Chancellor Philip Hammond again calling for ‘compromise’, it move could prove crucial in shaping the way the UK quits the EU.
Its amendment wording makes clear that next Wednesday - on the eve of the next Brussels summit - the usual orders of the House of Commons would not apply and that MPs would take control from government of the timetable of Parliament.
A series of ‘indicative’ votes would then be held on Brexit alternatives - probably the week after next.
Hammond said that it “certain” that MPs will vote on Thursday to authorise May to seek a delay to Brexit, but under the amendment that pause in the process would be accompanied by MPs being allowed to finally give a view on a string of ‘Plan Bs’ rather than just May’s deal.
Plans for a softer Brexit would need new talks with Brussels, but European Council president Donald Tusk indicated that the EU may be ready to offer a lengthy extension to negotiations if the UK wants to “rethink its Brexit strategy and build consensus around it”.
Mr Tusk said he would appeal to leaders at a Brussels summit on March 21 to be “open to a long extension if the UK finds it necessary”.
MPs will vote on a Government motion proposing to seek a delay in the date of Brexit from March 29 to June 30 if the Commons approves May’s Withdrawal Agreement in a third “meaningful vote” by next Wednesday.
The motion warns that if the deal, already rejected by 230 votes in January and 149 this week, fails again, the UK may have to accept a longer extension and take part in European Parliament elections in May.
Any extension must be approved unanimously by the 27 remaining EU states.
Meanwhile, May’s hopes of pushing her deal a third time before MPs could be scuppered by a late challenge by an amendment tabled by Labour’s Chris Bryant. It underlines Parliamentary conventions that the same motion cannot be re-tabled multiple times if already defeated.
Commons Speaker John Bercow indicated on Wednesday that he would give a ruling on the issue soon.
Hammond again made clear he would back an alternative to the PM’s own plans, telling SkyNews: “It is clear the House of Commons has to find a consensus around something, and if it is not the Prime Minister’s deal, I think it will be something that is much less to the taste of those of the hard Brexit wing of my party.
“I would be delighted if a consensus emerges behind the Prime Minister’s deal over the next day or two. But I think we also have to explore other options for Parliament to express a view about how we resolve this impasse.”
May has embarked on a fresh move to win round the DUP and the European Research Group (ERG) of backbench Tory Brexiteers, possibly with tweaks to the Attorney General’s legal advice on the deal.
However, DUP sources have told HuffPost that they will not tolerate the current deal and the ERG appears split over whether more of its members will cave to pressure in time for any third vote next week.