MPs returned to Westminster today, and amid the furore – with Attorney General Geoffrey Cox’s statement to the House, urgent questions from a slew of MPs, Sam Gyimah’s official defection to the Liberal Democrats and a performance by the Prime Minister – one unanswered question persists: despite everything, can Boris Johnson get a deal through Parliament, and if so, how?

Let’s go back to basics. Johnson entered Number 10 on the pledge that he would take the UK out of the EU “do or die” on 31st October. His route to a no deal exit seems, for now, to have been scuppered. Parliament is denying the government an election until the threat of no deal is dead. A deal looks like the only way out of reneging on his central campaign promise.

If so, he needs to work something out with the EU, get the backing of Macron and Merkel, appease Dublin, somehow sell it to a Parliament where he has nothing close to a majority, and pass the necessary legislation, all in just over a month. The usual health warning applies: Johnson could be removed by Parliament at any time, and we might see an early election happen anyway, after the Commons has passed further watertight legislation that precludes a no deal exit on 31st October.

Working back from the crucial date of the European Council meeting on the 17th and 18th October, what does Johnson need to do before then? The backstop is the persistent thorn in his side. He needs to find away around the impasse which prevented Theresa May’s Withdrawal Agreement from passing three separate times.

So long as the backstop is there, there will be no majority for the deal. But, Dublin won’t back any deal without a backstop. A while back May floated the idea of a Northern Ireland only backstop, which was acceptable to the EU, before abandoning it altogether at the behest of the DUP, who propped her up.

Since Boris Johnson has no majority, having expelled 21 Tory rebels early September, the DUP are functionally obsolete to him. Could he sneak through a deal with a Northern Ireland only backstop?

Possibly. But Boris Johnson himself has said that’s not a route he’s prepared to go down. However, the general assumption is that he, alongside EU leaders, are working on a solution that operates like a Northern Ireland only backstop in everything but name. Call it the Special Political Resolution, New Economic Provision, or whatever. Change the name, change the font, and maybe then Johnson has something approaching a workable deal.

Then what has to happen? Let’s say that by somewhere around October 10th Johnson has some kind of formal proposition for the EU, they give their general assent, on the condition that Johnson could find a majority for it in the House. A bill could be introduced, taking in concessions on workers rights and so on to rebel Labour MPs who want to leave.

The EU, crucially, is unlikely to want to sign something that will suffer the same fate in parliament as May’s deal did.

So, we might see, before the Council summit on 17th October, Johnson putting the new proposition to the Commons either as a bill or even an indicative vote to prove to the EU that he can find a majority for this new and improved (but not much) version of May’s Withdrawal Agreement.

Will he get the support he needs? Since revoking Article 50 is official Liberal Democrat policy, its 18 MPs will vote against. And we can expect the same from the SNP, Plaid and the Greens. With the Change UK MPs, too, that’s 63 definite votes against the deal. If Labour find an excuse to whip against it, which they likely will, we can add 246 votes to the anti-deal forces. But there could be anywhere between 5 and 25 Labour rebels – those who hold seats in Leave voting constituencies, and those who have been long time eurosceptics, and those who just want this all to end. If all 288 current Tories support Johnson’s deal, he needs to find around forty votes for a safe majority. Those votes would have to come from the now-expelled Conservative rebels who voted for May’s deal earlier in the year, and the higher end of the estimated Labour rebels. Let’s not forget that we don’t know which way the Brexiteer Tory ERG group will go. Whatever votes he loses in the ERG will need to be made up by even more Labour rebels. It’s very tight – but the maths might work.

Meanwhile, the clock is ticking. If Johnson can prove the Commons is with him for a deal in an indicative vote, he can move his proposal to the EU Summit, sign it, bring it back to the Commons for a confirmatory vote, which he will expect to win having won an indicative vote and, miraculously, have passed a deal.

Then, perversely, he might even actually get away with requesting a short extension of a few weeks for the Commons and the government to get its ducks in a row, working round the clock to pass the necessary legislation, and leave the EU with a deal some short way into November.

If it sounds implausible that’s because it is a long shot for Johnson. But amid the chaos of parliament returning, and a somewhat humiliated if defiant prime minister, we shouldn’t forget that there is a landing zone for a deal. It is small but the possibility is there.

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