If Theresa May delays the Brexit vote, what then?
You may have thought the vote in Parliament on Tuesday night was an important moment and deadline for how and whether the UK leaves the European Union.
I did. But I was wrong.
Because today the prime minister may decide to pull the vote (which she can do pretty easily, I am told by a minister, because of the way the motion for the vote is worded).
She will do that, her colleagues inform me, if she is facing defeat by the kind of colossal margin that would completely undermine confidence in her ability to govern - so more than 100 votes.
And right now, the margin of her personal humiliation looks considerably greater than that.
So what would it mean to pull the vote?
Well there is zero chance of her securing the kind of concessions from EU leaders this week at the regular EU council meeting that could turn that scale of Commons defeat into victory.
Sources in European capitals say the most EU government heads could offer would be some non-binding warm words about how they, like the prime minister, hope that the so-called backstop - so hated by Northern Ireland's DUP and Tory Brexiters - will never be implemented or will be of short duration.
Such friendly and supportive words will not turn the DUP and Tory Brexiters from enemies of the Brexit plan to its supporters. All they care about is the legal text of the Withdrawal Agreement. And absent that being opened up and changed - which it won't be this week - they will continue to stand in implacable oppositions to her Brexit plan.
So what can and will she do?
Well - and please move away from the ledge (NOW!) - she could try to re-open negotiations with the EU in a more fundamental way over Christmas and in January.
Because the hard deadline for her is in fact 21 January - which is when (under yet another successful Dominic Grieve initiative, enshrined in the EU Withdrawal Act), if there is no agreed deal, she is obliged to present a plan to parliament about what on earth she does next.
Now it is possible that her own Tory Brexiter MPs will not tolerate her shelving the vote. They want her plan dead and dead now. So they may - finally - see any further prevarication as all the cause they need to try and oust her.
That is the big risk for her, personally.
If she is to keep them on side, she may have to claim that she has been converted to their cause (yes I know that seems implausible).
One idea - put to me by a Whitehall rather than political source - is that she could tell the EU that unless the EU abandons the backstop, the UK would simply leave the EU on 29 March without a transition and via what is known as a hard Brexit, BUT that the UK would refrain from imposing any checks at its borders, either in the island of Ireland or at any of Great Britain's ports.
This would call the EU's bluff: it would mean that if Brexit were to be chaotic and economically disastrous, and if the border in Ireland were to harden in a way that promoted crime and terrorism, that would be at the EU's discretion, not the UK's (it's not a million miles from the tough negotiating stance currently being used by the Swiss, in their attempt to ward off the EU trying to give a greater role to the European Court of Justice in adjudicating single-market disputes - but the Swiss have less to lose than the UK).
This would he the ultimate in hardball negotiating, by May (so yes, implausible again).
It would keep onside most of the Tory Brexiters. But it would probably alienate a majority in parliament, because of the risk that it could all go horribly, appallingly wrong (it could lead to a disastrous Brexit, and could also damage diplomatic relations between the UK and EU for years to come).
The point, which you surely know by now, is that there is no Brexit available that doesn't alienate at least one constituency deemed important by the prime minister.
She attempted a Brexit whose explicit aim was to reconcile irreconcilable groups (Brexiters and DUP on the one hand, Remainers on the other; the EU 27 and Brexit voters). That failed. Her negotiated plan is in the dustbin of history.
To Brexit is to choose. May can duck her choice no longer (or at least not for very much longer!).