Theresa May fails to keep promise that UK won't be in the backstop indefinitely

Those Tory Brexiter MPs who WANT to believe the EU has no desire to trap the UK in the customs union via the Northern Ireland backstop will be reassured by the agreement between Theresa May and Jean-Claude Juncker on a new legal instrument saying the EU must negotiate in good faith to avoid the backstop coming into force at all or for long.

They will also be encouraged by a change to the UK/EU political declaration that will step up work on putting in place alternative arrangements to obviate the need for the backstop - and by the UK Government’s declaration of what it would do to get out of the backstop if the EU is ever seen to be trying to imprison the country in the backstop.

But by the Government’s own admission, in the motion it has laid before Parliament, what these new UK/EU compacts do is "reduce the risk the UK could be held in the backstop indefinitely" but they do not eliminate it.

And there is the petard that will probably hoist the prime minister and her Brexit deal.

Because in backing the so-called Brady amendment at the end of January, she promised to guarantee beyond any doubt that the backstop could not be forever.

She has failed.

That means too few Tory Brexiter MPs will change their mind that her form of Brexit is a pact with the EU that no proudly independent nation could ever sign.

Even Northern Ireland’s DUP MPs, who are desperate to cease their opposition to the PM’s deal and really want to back the PM at the last, will struggle to justify doing so.

DUP MPs such as Arlene Foster and Nigel Dodds will be reluctant to vote for May's deal, despite wanting to side with the PM. Credit: PA

Which means I can see no route to victory for her in the meaningful vote tonight - which I would expect her to lose by another significant margin.

If so, she would face decisions of moment for all of us and for herself.

Would she work with Parliament to take a no-deal Brexit off the table - or stick to her own official policy and work against MPs who want a different Brexit or even no Brexit at all?

And would she take this latest and perhaps greatest diplomatic and political humiliation on the chin, as she has so many others, and battle on.

Or could she decide that she has done what she can to execute the revealed will of the British people to leave the EU, against the constant opposition of MPs from all sides, and it may now be time for another prime minister to finish the job.