What are the possible scenarios?
The EU is expected to publish a letter of clarification emphasising that any use of the Northern Ireland backstop would only ever be temporary. Theresa May will make a public appeal for support in a speech in Stoke this morning, while MPs move on to day four of the Brexit debate in the Commons with Philip Hammond, the chancellor, closing proceedings.
If May allows it, MPs will finally get to vote on her deal. The Speaker will select the amendments to be voted on. The one to watch is Hilary Benn’s move to reject May’s deal and no deal and give MPs a say in what happens next. May will speak just before voting starts at 7pm. Jeremy Corbyn could immediately demand to hold a vote of no confidence if May loses.
If May were to prevail, the DUP have threatened to abandon the confidence and supply agreement, leaving the Tories without an overall majority. A confidence vote could be held but, in this scenario, the DUP have said they will support the Conservatives to try to get the Brexit deal renegotiated. May may find she is not able to stay on if she suffers a heavy defeat for her deal – 80-plus rebels.
Thursday and beyond
May could dash to Brussels to see if there is any hope in renegotiating. She would have until the close of business on 21 January to unveil a plan B; MPs would then debate and vote on that later that week. Tories pushing for a soft Brexit could break ranks; May could seek a general election; or campaigners for a second referendum could find they have a chance to prevail.