Now the Brexit deal has been signed off in Brussels, attention turns to Westminster.
MPs will get their say on whether they approve of the deal or not. Several days of debate will be followed by what's known as the "meaningful vote". This is expected to take place in the week beginning 10 December.
Any attempt to work out the parliamentary arithmetic can only be an estimate so all numbers should be treated with caution. As things stand, though, there seems to be a majority against the proposed deal.
Theresa May relies on the 10 Democratic Unionist Party MPs for her majority in the House of Commons. Their opposition to the proposed deal alone could make winning the vote tricky but the prime minister's problems don't end there.
Some 57 Conservative MPs have signed up to the StandUp4Brexit campaign which argues that the proposed deal leaves the UK too close to the EU. (That includes Charlie Elphicke who is currently suspended from the party but generally votes with the government.)
Added to those are the seven pro-Brexit MPs who resigned from government or party jobs on 15 November. And several more who have publicly stated they are opposed to the deal.
Then there are, perhaps, a further dozen or so Conservative MPs from the Remain wing of the party who support the People's Vote campaign for another referendum or would like a closer relationship with the EU.
All in all, there are around 80-90 Tories currently set to defy the government.
Some of them have only said they can't support the deal which, perhaps, suggests, they might abstain when it comes to the crucial vote. But others are more hardline.
On the other side of the calculation, there are a handful of pro-Brexit Labour MPs who might back the deal. And a further group who could vote for it to stop the possible alternative of a "no deal" Brexit.
There's also one Liberal Democrat MP, Stephen Lloyd, who says he'll vote in favour of the deal to fulfil a pledge he made to his constituents.
As things stand, though, this group isn't big enough to outweigh the DUP and Conservative rebels.
Things can change of course. Mrs May will hope to persuade some of the rebels and more opposition MPs. But she has a long way to go.