Leave aside the theatrics of Spain’s last-minute objection over Gibraltar, the great European question is still whether Theresa May can get her deal through parliament. Nobody knows the answer to that. The prime minister has two plans, but no idea if they will work or not.

One of them involves persuading two groups of MPs in opposite directions. Last week I pointed out that Labour MPs risked pushing Britain out of the EU without a deal if they voted against the prime minister’s Brexit. That remains a possibility in the background, but since the agreement on Thursday on part two of the Brexit deal – the outline of the future trade relationship – everything has changed.

Now the threat to May comes from Brexiteers who say that her deal is worse than staying in the EU. Boris Johnson and Dominic Raab claim that they are not advocating staying in the EU, but if they are faced with a choice between May’s deal and staying in the EU, what else can they mean?

Of course they say what they really want is for us to leave without a deal – or a Canada-style free trade deal, which amounts to the same thing, because it is unacceptable to the EU unless it excludes Northern Ireland. But there is a majority in the Commons against a no-deal Brexit, so their choice could be May’s Brexit or no Brexit.

We have gone through the looking-glass to a world in which Philip Hammond, the chancellor and leading Remainer, said this morning we would be better off outside the EU, while a new movement of Brexiteers against Brexit has sprung up to argue, in effect, that we might as well stay in the EU.

The Tory Remainers are for Brexit while the Brexiteers are for Remain. It would be high comedy if we were not talking about people preparing to roll dice to decide the nation’s future.

So how does the Remainer-for-Brexit prime minister hope to win the votes in parliament? In two ways, I think: persuasion and attrition. First she has got to explain the deal. “She hasn’t managed to package it in a way that allows people to understand it,” one cabinet minister pointed out unhelpfully to James Forsyth of The Spectator.

Expect to hear over the next two or three weeks the reasons why Theresa May is confident Britain would not be permanently trapped in the backstop – the arrangements to guarantee an open border in Ireland. That is the part of the deal that has provoked the overblown rhetoric from the Brexiteers against Brexit brigade about our being a “colony” or a “vassal state”.

The prime minister and her small band of loyalists, now reinforced by another Remainer-for-Brexit, Amber Rudd, will argue that the backstop would be “mutually uncomfortable”. The UK government wouldn’t like the European Court of Justice having a say over parts of the Northern Ireland economy; while EU27 governments think British, especially Northern Irish, companies would have an unfair advantage because they would not be bound enough by EU law.

What is more, the UK government argues that there is no legal basis in Article 50 for a permanent arrangement – it is explicitly described as temporary in the legally binding withdrawal agreement.

This is, however, a rather technical sales pitch, up against the slogans of “Brexit in name only” and “EU vassalage”. In the end, the simple pitch will have to be that May’s deal takes us out of the EU, as the people wanted, but keeps us in a close economic relationship for the sake of jobs and living standards. A jobs-first Brexit, you might say.

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The second part of May’s plan to get her deal through parliament is attrition. One by one, she hopes to close off the other options. It would not be surprising if EU leaders rule out the idea of renegotiating the deal once they have formally approved it. (In any case the only likely alternative deal would be like Norway in a customs union: in effect non-voting EU membership, including free movement of people.)

Then there is the option of postponing Brexit while we have another referendum. Johnson and Raab ought to vote for that, but they won’t, and I still don’t think there are enough pro-EU MPs who would back it if they could have May’s deal instead. Once a final-say referendum has been defeated, the only options left would be May’s deal or leaving without a deal, and we know which way most MPs ought to go on that, even if we can’t be sure they will.