The Prime Minister is almost certain to face a crushing defeat in the Commons on Tuesday.
The question is not whether her Brexit deal will be rejected but by what margin - it is entirely possible Theresa May could suffer the greatest defeat of any modern Prime Minister.
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Any rebellion on the Tory backbenches in three figures will be considered a serious failure for No 10. A handful of rebels have rowed in behind the PM in the past 24 hours - but it was not clear whether some of those opposed the plan in the first place.
There are now multiple sets of MPs in Parliament working to influence what happens next.
Here's what we know about what could take place after the PM's plan is defeated.
May's next move
Theresa May speaks in Stoke on Trent in an effort to gather support for her deal. Image: Getty
Theresa May has been forced by the Commons to bring back her next set of ideas within three sitting days. This gives an effective deadline of Monday 21st of January to outline her view on the next steps. She will likely do this in a statement to the Commons.
She could use her loss on Tuesday to pressure EU leaders into proper concessions - particularly on the backstop issue.
But her opponents say anything less than striking out the backstop from the Withdrawal Agreement won't suffice. And the EU has repeatedly said that reopening negotiations is not going to happen.
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As such, she will be looking for something stronger than the letter she is likely to have secured from EU leaders - which will be published later.
She has other options to bring rebels around. She could, for example, set a date to step down. But it is thought the PM is not keen not to play this card unless she has to.
She could return to the Commons on Monday and attempt the vote again - if the number of rebels comes down, she could perhaps keep attempting the vote until she succeeds, possibly supported by Labour MPs who oppose a no deal exit.
Labour leader Jeremy Corbyn. Image: Getty
It is likely Jeremy Corbyn will table a motion of no confidence in the government this week in an attempt to force a general election.
At this stage it is unlikely that Mr Corbyn will secure the necessary votes in the Commons to make this a reality - but there is no limit on the number of times he could attempt to bring the government down.
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Tabling the motion is problematic for him though - it could embolden Labour MPs who want a second referendum.
Currently Labour policy says a general election should be tried for first - so if that genie is let out of the bottle and comes to nothing, a second vote could be argued for more loudly by many of Mr Corbyn's own parliamentarians.
Andrew Murrison. Image: UK Parliament
Tory backbencher Andrew Murrison is tabling an amendment - thought to have government backing - in an attempt to bring rebel MPs round.
The amendment supports Theresa May's deal, subject to a legal proviso stating that the backstop must end by December 31 2022.
It's likely that Brexit-backing MPs will argue that this doesn't have enough effect and won't be enough to set in stone a convincing backstop exit mechanism.
The Boles plot
Nick Boles. Image: UK Parliament
Meanwhile, Tories Nick Boles, Nicky Morgan and Oliver Letwin have come up with a cunning plan.
Should Mrs May's deal fail, they want control of the process handed to a poweful Commons committee of MPs - the Liasion Committee (made up of 36 select committee chairs).
It would have three weeks to come up with a deal that could get through Parliament.
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But this is controversial. The Chair of the committee, Sarah Wollaston, has already suggested it's not their role.
Likewise, handing control of the process to a remain majority committee of senior MPs is a very tough sell to Brexit voters.
They are set to outline this proposal in more detail this afternoon.
Anti-Brexit protestor Steve Bray. Image: Getty
While all this is fought over, planning for a second referendum has stepped up a notch.
Today Vince Cable, Chuka Umunna, Dominic Grieve and Ian Blackford will put their name to two draft bills paving the way for a second vote.
These could be tabled on Monday, setting in train the Parliamentary process for bringing about another referendum.
More MPs are likely to back the proposed legislation after Mrs May loses on Tuesday night.
Theresa May. Image: Getty
MPs will begin voting at 7pm on Tuesday, and the meaningful vote itself could take place as late as 10pm.
It's probable that Theresa May will immediately make a statement after the result comes in.
What she has to say - or what little new she has to offer - will set the course for her premiership and for the Brexit process, both of which may be approaching their final act.