Theresa May is in Strasbourg tonight trying to rescue her Brexit deal by securing a tweak to the terms of the infamous backstop.

But her Brexit deal, whether it is adjusted or not, is expected to be put to a vote in the Commons tomorrow, despite whisperings earlier during a day of high drama that she would pull the vote last minute while seeking any concessions from the EU.

May will likely face a second crushing defeat over her deal tomorrow, following a record-breaking defeat of 230 votes in January. The backstop, much-loathed by Brexiteers, was the biggest obstacle for May then, and remains the biggest obstacle for May now. Securing enough votes for her deal will depend on the EU offering some pretty serious concessions on the backstop, which they are unlikely to do.

On Friday, EU’s chief Brexit negotiator Michael Barnier did offer the UK some concessions, sort of. His non-concessionary concessions amounted to not much beyond a strengthened emphasis that the EU would try to prevent the UK falling into the backstop. It’s understood that May was forced to reject Barnier’s proposal, following an intervention by Attorney General Geoffrey Cox, since he did not see it going far enough to assuage the concerns of the anti-deal MPs.

In his talks with Brussels, Cox asked that principles of “reasonableness” be applied in assessing whether the EU is negotiating fairly in trying to keep the UK out of the backstop. That is as nebulous as it is implausible, and the Brexiteers don’t appear moved. Despite May and Cox’s efforts the backstop remains the sticking point, and the reason why May’s deal looks destined to fail in the Commons

The deal may not fall short by such a large majority as last time however, which is small comfort to the Prime Minister. The DUP, vocal critics of the deal, might support May last minute. But, even if the DUP get onside May still needs 106 MPs to change their mind. And it’s not looking good – May is putting to MPs an essentially identical question as last time. And while a few among the anti-deal MPs may be looking for a ladder to climb down so they can back the deal, the tactics haven’t worked so far and the parliamentary arithmetic still works against her.

Assuming May’s deal fails tomorrow (you would be pretty safe to do so absent a breakthrough late tonight), MPs have been promised two further votes. The first, on Wednesday, will ask MPs whether the Commons should rule out a no deal exit.

The second, most likely on Thursday, will ask MPs to vote on extending Article 50. There are a few problems here. Extending Article 50 requires the unanimous consent of all 27 EU member states. And, the EU has made it abundantly clear that it will not extend Article 50 in the absence of a clear plan from the government about how they intend to use the extension.

Extending Article 50 will also require the UK to take part in the upcoming MEP elections, which both the EU and the UK want to avoid.

So, it’s at best uncertain whether the EU would offer the UK any extension at all. And when it comes to ruling out no deal, there is an even greater impasse. Ruling out a no deal Brexit does nothing concrete in the way of stopping it from happening. If there is no extension to Article 50, and no deal approved by 29th March, the UK will leave the EU without a deal whether the MPs like it or not.

There will likely be a series of amendments to be voted on. Another (probably failed) attempt from the second referendum crowd is likely. MPs favouring a Norway deal will try for that again too. However, there simply aren’t the numbers in parliament for these to be meaningful challenges, yet.

Speaking of insufficient attempts to pacify the concerns of the Brexiteers, Irish foreign minister Simon Coveney made a statement outside Leinster House this afternoon. He said: “We are very clear that the withdrawal agreement can’t change in terms of text. But we also want to be helpful in terms of providing the clarity and reassurance that is needed in Westminster that the backstop is intended to be temporary. Nobody is looking to trap anybody anywhere permanently, but the backstop needs to be there and it needs to be robust.”

It is an understandable statement but unlikely to move MPs. The next steps for May are terribly tricky. Time is really running out. Number 10’s plan that MPs will realise Brexit has reached crisis point and capitulate to supporting the deal doesn’t look like it’s working. Theresa May needs a miracle and it would be out of character for Juncker to supply it.