This is why MPs are voting on Brexit again tonight – and why this time it really matters

The Cooper amendment will likely be narrowly defeated – but what exactly does that mean?

There are likely to be two big votes tonight. The one on Yvette Cooper’s amendment will come first. It could be historic, because it tries to take control of Brexit away from the government – in order to take a no-deal Brexit off the table in a legally binding way.

The prime minister this afternoon described this amendment as “deeply misguided”, because it would “allow parliament to usurp the role of the executive”.

That vote looks as if it will be close, although I think the chances are that it will lose narrowly. Cooper will not get a full turnout from Labour MPs. Many of them think they have to deliver the vote of the British people to leave the EU, and they are worried about being seen as trying to “block Brexit”.

There is a hard core who would vote against the Cooper plan, but a larger number who might abstain rather than be accused of trying to frustrate the will of the people. There were seven Labour MPs who either voted for the prime minister’s deal two weeks ago, or who voted against it because they want a no-deal Brexit. But there is a larger group who disagree with delaying the UK’s departure from the EU. They include Caroline Flint, who called it a “disaster”.

On the other side, there are many Conservative MPs who are desperate to avoid leaving the EU without a deal, who are sympathetic to what Cooper is trying to do, but who are being swayed by May’s argument that they will get another chance to stop a no-deal later. She appealed to them today not to muffle the message sent from the House of Commons to the EU.

She wants to use the second vote, on an amendment tabled by Sir Graham Brady, the leader of Conservative backbenchers, as leverage in her negotiations with the EU. The amendment wants to replace the backstop plan in the withdrawal agreement for keeping an open border in Ireland with “alternative arrangements”. No one knows what these might be, except for a return to the old idea of using technology to avoid customs posts on the border – an idea that neither the EU nor the UK government thinks is workable.

All the same, the prime minister confirmed to the Commons that she is seeking “significant and legally binding change to the withdrawal agreement”.

She admitted: “Negotiating such a change will not be easy. It is a move for which I know there is limited appetite among our European partners. But I believe that with a mandate from this House I can secure such a change.”

Even so, and despite her plea – “I need the strongest possible support behind me” – it is going to be hard for her to win the vote on the Brady amendment this evening. The DUP has supported it, but there is a small group of hard-Brexit Tory MPs who disagree with it. They think that “alternative arrangements” is a vague phrase designed to allow a clever use of words to rebrand the backstop, which uses a UK-wide temporary customs union and some single market rules in Northern Ireland to avoid a hard border.

On the other side of the Tory party, Sarah Wollaston says she won’t support the Brady amendment, and it will be hard to persuade other pro-EU MPs such as Anna Soubry and Kenneth Clarke to vote to re-open negotiations with Brussels.

So it is possible that the House of Commons will vote for none of the specific options put to it tonight. The main opposition amendment tabled by Jeremy Corbyn is unlikely to succeed, because it won’t attract Tory rebels. If the Cooper amendment is going to lose, a complementary amendment tabled by Dominic Grieve, which will be voted on first if it is pressed to a vote, will also probably lose. It is intended to take control of more parliamentary days from the government to give backbenchers more chances to make proposals.

Finally, there is also an amendment in the name of Caroline Spelman, Tory former cabinet minister, simply seeking to rule out a no-deal Brexit. Unlike the Cooper amendment, however, this amendment has no legal force, and would simply be an expression of MPs’ views.

Theresa May opened the debate by saying the House of Commons knows what it is against, but not what it is for.

If it fails to vote in favour of any of the amendments today, as May once said herself, nothing will have changed.