Here’s what might happen after tomorrow’s vote. . .

HOLD THE VOTE LATER

With more than 100 Tory MPs suggesting they will vote against the deal, together with Labour, the Lib Dems and the SNP, a defeat tomorrow night seems most likely.

If Theresa May doesn’t quit, she could go to Brussels to try to seek a clear concession of a time limit on the backstop, or a unilateral exit mechanism for the UK. A second Commons vote on the deal would then take place before Christmas. If the PM wins, Brexit goes through.

TORY REBELLION

With Europe unlikely to provide the concessions Ms May asks for, Tory backbenchers could decide to try to get rid of their leader. If a 48-letter threshold is reached, a no-confidence vote among Tory MPs would follow.

Ms May could win this, but if she does not, challengers such as Boris Johnson would be able to enter the leadership fray. A more Brexit-friendly leader could go on to try to negotiate a looser Canadastyle deal, which would involve more problems with the backstop.

NO-CONFIDENCE VOTE AND ELECTION

Labour could table a motion of no confidence in the government. This could even happen if the deal passes because the DUP – which props Ms May up – has said it will not support the current agreement.

If the Tories lose a vote of no confidence – and Labour is then unable to form a minority administration – a snap election would be held. This would raise the prospect of Jeremy Corbyn taking the keys to No. 10 and attempting to negotiate his own Brexit deal.

THE NORWAY OPTION

If Ms May’s plan is voted down, an MP could put down an amendment calling on Britain to join the European Economic Area, which allows non-EU members access to the single market. However, Labour opposes such a deal, and Tory Brexiteers would oppose it because it means continued freedom of movement.

SECOND REFERENDUM

A Remain-supporting MP could put down an amendment calling for a referendum on Ms May’s deal. Such an outcome would require Brussels to agree to defer Brexit day.

NO DEAL

If Ms May’s deal is defeated, and the EU offers no more concessions, then Britain could crash out without a deal.