The government’s efforts to get changes to the backstop have run into a brick wall in Brussels. The EU thinks, with justification, that MPs won’t allow no deal and so feels under no pressure to make significant concessions. As I write in The Sun this morning, one minister fully briefed on the negotiations says ‘we’re at what the hell do we do time’

But without a change to the backstop, Theresa May’s deal is going down to another heavy defeat on Tuesday. That won’t be the end of the matter, though. For the next day, parliament will vote against leaving on March 29th with no deal. Parliament will then almost certainly vote to request an extension to Article 50.

At this moment, the UK would be in the EU’s hands. As one weary Number 10 source admits, ‘They’d be in a position of being able to dictate terms.’ It would be up to the EU to decide whether to grant an extension, how long it would be for and what conditions would be attached to it.

The EU would almost certainly grant one. But what terms it would come with remains to be seen.

What should worry those MPs who are voting against May’s deal because it is not a clean enough Brexit, is what parliament would do with this extension. I understand that unless the government indicates that it will allow the Commons to vote on various Brexit options, an amendment will be tacked onto the extension vote to ensure that ‘indicative votes’ are held.

These votes would be held on the 25th of March and the Commons would move to bind the government to negotiate what it wants it to. Ministers would have to report back regularly to the Commons on the progress they are making. May might be in office, but she would not be in power.

It is inevitable that the Brexit the Commons would mandate would be softer than May’s deal.

So, why then are so many Brexiteers not voting for May’s deal? Well, the problem is that many of them regard her deal as so flawed they have no desire to rescue it. They would, in the words of one Cabinet Minister, ‘rather their hands be clean of all this’. But this isn’t practical politics.

Is there any hope of avoiding this crisis? Today, it looks unlikely. But the DUP do want a deal. While they won’t accept the backstop as it currently is and were, in the words of one source, ‘not entirely happy’ with the proposal Geoffrey Cox took to Brussels, they are eager for an agreement.

If progress on the backstop was combined with a commitment from May that she would step down before phase 2 of the negotiations, then the deal might pass. I understand that a leading Brexiteer backbencher conveyed this message to influential figures in the government this week.