If they table two motions. They can vote against the deal.
And against a no deal.
Which leaves us....... well, I haven't a clue.
not over by a longshot.
“The Commons showdown is set to take place between 9.30am and 2.30pm.
Boris Johnson will address the Commons and lay out his deal – taking questions from across the House. He will give a statement on the EU council and how it went.
Later in the day MPs will put amendments to Boris’ deal, and the Speaker will choose whether to vote on them, and if they have enough support.
The final vote will be on the deal as a whole – and any amendments which pass with it.
WHAT IF IT PASSES?
If it passes, Britain will be on track to leave the EU on October 31.
But there are a whole host of other Bills that must be signed off too – such as on trade, agriculture and food.
The PM will have to bring those forward in the coming days if he wants to leave on time – and MPs will have to vote in favour of them all.
WHAT IF IT FAILS?
If it does not pass, then under the Benn Act Boris Johnson will be forced to ask the EU for another delay to Brexit on Saturday evening.
Boris is legally obliged to go cap in hand to the EU and ask them for another extension if there’s no deal signed off.
Strategically, the PM could try and go for a No Deal Brexit, but he will likely need an election to deliver that as MPs won’t support it.
No10 has already confirmed they will have a vote on a deal, but not a vote on whether to go for No Deal.
If Boris wanted an election, he would likely have to admit defeat and delay Brexit.
Jeremy Corbyn won’t back an election until an extension is sealed with the bloc.
Boris could decide to bite the bullet and go for a delay, feeling he has no option left as MPs have rejected his deal, and thinking that if he wins a bigger majority he can push his deal through at a later date.
The PM could try yet again for more tweaks to the deal with the EU, but the bloc are unlikely to want to do this.
If it gets thrown out then it’s up to the EU27 leaders to decide whether they want to give the PM another extension – they could say ‘no thanks, you’re leaving no matter what’.
However, today Jean Claude Juncker has said that there will be no more extensions.
Mr Tusk was slightly warmer to the idea of a delay, saying he would speak to EU leaders if Boris did request one.
It’s up to the 27 EU member states if they want to to give us one, not Mr Juncker or Mr Tusk.
But several of them have said that if there was a good reason for an extension – such as a second referendum or an election, then they could allow one”