Brexit: The prime minister blinked
Whatever else happens in the next two hours, Theresa May did what she previously said was impossible, and committed herself to try to reopen the divorce deal, the legal text negotiated over two years with 27 other countries.
After a fortnight of swearing it was not going to happen, her dire predicament and continued protest from Eurosceptics moved the prime minister to this point.
This path was probably, in the end, the one that she would always have to choose, having made clear in recent days that she would aim to preserve Tory party unity, to try to stay in power, rather than switch to pursue a closer relationship with the EU.
- Government supports Irish backstop change
- A guide to MPs' Brexit amendments
- No-deal Brexit 'to leave shelves empty'
With the bulk of Brexiteers and the unionist DUP now on side, it was a straightforward political choice - even if, as a policy, it's been dismissed as chasing a fantasy.
Having promised to change part of it, the prime minister is likely to have more support for her deal, by the end of tonight.
But there are still strong demands for her to rule out leaving without a formal deal across Parliament.
There is still no sign that the EU is ready straight away to grant any of the revisions she may demand.
The move, as ever, is designed to get the prime minister more smoothly through the day. But the reversal solves only one of Theresa May's problems, and only solves it for now.