Assuming that the agreement has been lowered, the margin of defeat is important.
We should lose about 30, 40 or maybe even 50 votes, so we are expected to stand up in Parliament and say that he will return to Brussels and try to change the agreement.
If minor concessions were granted with the EU, this could be enough to persuade some British legislators to take sides in May with a second parliamentary vote.
A warning in this regard is that the rest of the EU has shown little appetite to reopen the talks. The President of the European Commission Jean-Claude Juncker warned the United Kingdom that the agreement on the Brexit of May "is the only possible agreement".
If it were to lose heavily, chaos is once again able to descend on British politics.
The range of results ranges from a challenge to leadership, a resignation in May, a general election in the UK, a second referendum on membership in the EU, a temporary stop on the withdrawal of Britain, or a sort of combination of all the previous ones.