It's more than a month before the earliest date a Brexit deal is likely to be agreed but speculation at Westminster is already focused on how Theresa May will assemble a majority of MPs behind it. At prime minister's questions on Wednesday, former Conservative chancellor Ken Clarke asked her about the challenge of winning parliamentary approval for the deal.
"Does she ... accept that the maths makes it obvious that that majority can only be obtained if the agreement retains the support of the pro-European Conservative backbenchers in this House and wins the support of a significant number of Labour pro-European backbenchers? That would reveal that the hardline Eurosceptic views of the Bennites on the Labour front bench and the right-wing nationalists in our party are a minority in this parliament. Will she therefore proceed courageously on that basis in the formidable task that lies ahead of her?" he said.
The prime minister's allies are confident that the number of Conservative Brexiteers voting against a deal will be well below the 40 claimed by former Brexit minister Steve Baker this week. But with a working majority of about 13, including the DUP's votes, any rebellion that gets into double digits is a threat to the government.
Labour support
Government whips hope they can persuade up to three dozen Labour MPs to back May’s Brexit deal rather than risk a no-deal scenario or be seen to block Britain’s departure from the EU. May, who called on Wednesday for MPs from all parties to “put the national interest first”, appears to be targeting Labour MPs who represent very pro-Brexit seats as well as the party’s pro-European wing.
Jeremy Corbyn’s spokesman said there was no evidence that any significant number of Labour MPs would vote for a deal that did not satisfy the tests the party has set out.
"It's quite clear that the prime minister is in a very difficult position," he said. "She spent most of the last two years negotiating with her own party and not the European Union and the prospects of a significant rebellion among her own MPs is pretty clear. So it's not surprising that she is trying to find support elsewhere. We've made very clear what kind of package we would support and what we won't."
With so little room for manoeuvre, the prime minister will struggle to find a majority for any deal she brings back from Brussels, particularly if she has to do so without the support of the DUP.