The new Brexit deal has been agreed between the EU and the UK. Theresa May, the former prime minister, would be forgiven for flicking through it and thinking "nothing has changed". But, while small in number, there are some significant modifications.
And on Saturday we will learn whether the most important thing of all has changed – does the deal have the backing of a majority of MPs?
A number of critical groups will be decisive in Saturday's vote.
The DUP won’t back Johnson’s brexit deal and it is increasingly hard to see a deal they would support
The DUP have said they won’t accept a deal that puts a customs border between Northern Ireland and Great Britain – even if, in principle, Northern Ireland remain in the UK customs territory. They have previously rejected a customs union to avoid a UK-EU customs border altogether. That really only leaves one place where they would accept such checks – on the island of Ireland. And that is something which Boris Johnson will no longer back.
The DUP are also unhappy with the consent mechanism, which allows a simple majority in Stormont to decide whether to continue with the agreed relationship of NI with the EU. The likelihood is that majority would want to stay close. The DUP wanted a veto, but this deal doesn’t give them one.
Johnson clearly decided not to wait for the DUP’s go-ahead. He still has time to try to tempt them over to his column with a cash-for-constitutional-principles deal, but while the DUP are skilled in brinkmanship they may not crack this time. In the past the party has been seen as a bellwether for Tory Brexiteers (and Labour’s Kate Hoey), but this time around the DUP might find they have fewer friends than they thought.
A group of Labour MPs wrote to Donald Tusk and Jean--Claude Juncker earlier in the month to stress their eagerness for a deal. But the EU are all too familiar with promises of Labour MPs riding to the rescue. They were assured time after time by Theresa May that Labour MPs – with the tally possibly as high as 50 - wanted to get Brexit done. In the end, only five voted for May’s deal at the third time of asking and two abstained.
Many of those hold-outs will be regretting their decision. This deal does much less for them than the May deal – there’s no UK wide customs union to support manufacturing industries in their seats, there are no legal guarantees on workers’ rights and there is the prospect of a much harder Brexit once the future relationship is negotiated.
Johnson could try to offer concessions outside of the deal, as with the DUP. Or he might just hope that the prospect of a general election, where they would be forced to explain Labour’s second referendum position to their leave constituencies, is enough to prompt rebellions. But Labour whips will be looking to whittle down the number of rebels and, judging on the reactions of those 19 MPs who had signed the letter to the EU, it won’t be too difficult. But the rebel number won't fall to zero, and the exact number of Labour pro-dealers could yet be the deciding factor on Saturday.
The other important group will be the independents. Almost 80 MPs have switched party allegiances over the course of this Parliament – and many of them have become independents. They won’t vote in a united block – even the 21 rebels that Johnson removed from the Conservative Party will have different views. Some want another referendum. But some want Brexit done and have always backed a deal. Johnson may offer them a route back into the party in return for their vote.
The overwhelming majority are likely to support the prime minister. But there might be a very small handful – the previous chancellor, Philip Hammond, being one – for whom being an independent might give them licence to vote against the deal in a way they wouldn’t have if they still had the whip – particularly if they think they can rely on the EU Withdrawal (No.2) Act to prevent no deal.
If Johnson fails, then many expect a Brexit extension and a general election to be inevitable. And if he is successful then it is likely to be by a very narrow margin.
The EU Withdrawal (No.2) Act, legislating against no deal on October 31, would fall away. There would be two weeks to ratify the deal and pass the Withdrawal Agreement Bill (WAB) or the UK would leave without a deal – unless Parliament finds another way to assert itself.
Theresa May attempted to publish the (WAB) – the legislation implementing her deal – and the bill's contents were so controversial that it prompted the end of her term in Downing Street. Johnson’s bill won’t have a referendum clause, but it will contain contentious elements. If he cobbles together a slim majority to get his deal through Parliament then it could evaporate on sight of the legislation. And at that point lots could change – MPs might change their mind on the merits of this deal versus no deal, or we could see more emergency legislation.
However Saturday’s vote turns out, it is just the first hurdle in Parliament that awaits Boris Johnson.