Four scenarios that could await the PM

Boris Johnson faces a challenge to win today’s vote in the House of Commons, with the DUP confirming it will vote against the UK Government’s new Brexit deal.

A total of 635 votes will be in play when the deal is debated.

This means the Government will need at least 318 to be certain of a majority.

Here are four scenarios for how the vote could unfold.

Scenario one

If every Conservative MP who is able to vote also backs the deal, this gives the government 285 votes – 33 votes short of a majority.

This shortfall could be met through a combination of votes from Labour and independent MPS.

There were five Labour MPS who voted on March 29 for Theresa May’s version of the Withdrawal Agreement.

It is not clear how all of them intend to vote on Boris Johnson’s deal, though John Mann has said he will back it.

A small handful of other Labour MPS have indicated they might consider backing Mr Johnson’s deal.

Scenario two

Not every Conservative MP may decide to back the government.

A handful might follow the example of the DUP and vote against.

If 10 of them do so, this would reduce the number of Tories in favour to 275, leaving the government 43 votes short of a majority.

However, it could be the case that more Labour MPS than expected support Boris Johnson’s deal.

Were 20 Labour MPS to vote in favour, plus 23 independents, then this – plus the 275 Tory MPS – would be enough to get the government to 318.

Scenario three

If Labour leader Jeremy Corbyn manages to keep the number of Labour MPS backing the government to – at most – a dozen and a handful of Conservatives vote against the deal, then Boris Johnson could be in trouble.

In this scenario, 275 Tories vote in favour, along with 23 independents but only 12 Labour MPS. This would leave the government with 310 votes, eight short of a majority.

Scenario four

MPS might vote in favour of an amendment that requires the government to ask for an extension if other Brexit-related legislation has not been passed before October 31.

This could mean that the deal is approved in principle today, but the UK would not leave the EU until the full Withdrawal Agreement – which implements the deal – is also passed.

The amendment has been submitted by Sir Oliver Letwin, one of the group of former Conservative MPS who lost the Tory whip when voting for the Benn Act.

If this amendment becomes part of the government motion today, then a simple yes/no vote on the overall motion could turn into a choice between “yes by October 31” and “yes but with more time”.

Assuming the government backs “yes by October 31”, this could prompt many of those independent MPS to back “yes but with more time” and leave the government short.