Britain is bracing for a historic showdown in Parliament on Saturday as Prime Minister Boris Johnson scrambles to win backing by MPs for his Brexit deal with the European Union.
Mr. Johnson and EU leaders announced the agreement on Thursday, hailing it as a major breakthrough that finally resolves the thorny issue of how to keep the Irish border open after Brexit. The deal will essentially keep Northern Ireland aligned with EU regulations, but it will also allow Mr. Johnson to argue that the entire United Kingdom is leaving the bloc on Oct. 31.
The Prime Minister now has to win parliamentary backing for the deal during a special session on Saturday, and that won’t be easy. The House of Commons has already rejected three previous Brexit deals struck by his predecessor, Theresa May. Mr. Johnson’s Conservatives also don’t have a majority in the Commons, and their ally, Northern Ireland’s Democratic Unionist Party, has come out against the agreement.
Mr. Johnson spent Friday cajoling and arm-twisting MPs in a frantic effort to get the deal approved. He has made progress, and experts give him a decent chance of succeeding where Ms. May failed. That’s partly because his Brexit deal addresses many of the concerns shared by a group of fellow Conservative MPs who thwarted Ms. May’s agreement. There’s also far more fatigue among MPs, and the public, about Brexit, and a growing number of MPs have said they would vote for the deal to end the saga.
“I think [Mr. Johnson] has a better chance than people think,” said Tim Bale, a professor of politics at Queen Mary, University of London. “He has a bit of momentum behind him.”
Tony Travers, a professor in the department of government at the London School of Economics, said many MPs “would desperately like to get this stage of Brexit out of the way. I think they feel emotionally drained.” He added that “on balance, I think it’s a bit more likely to go through than not.”
The parliamentary arithmetic remains tricky for the Prime Minister. There are 650 MPs in the House of Commons, although 11 don’t vote: the Speaker, three deputies and seven members of Parliament from Northern Ireland’s Sinn Fein party who never take their seats. That leaves 639 MPs, which means Mr. Johnson needs 320 votes to win, barring absences or abstentions. His Conservatives have 287 MPs, and they don’t always toe the line. Even if they all vote for the agreement, Mr. Johnson still needs to find support among the 21 Tory MPs he expelled from the party last month after they sided with the opposition over Brexit. He’ll also have to convince some Tory MPs who resigned from the party’s caucus because of his Brexit strategy. That includes former cabinet ministers Amber Rudd and Mr. Johnson’s brother Jo Johnson. And that’s still not enough to win.
The key to Mr. Johnson’s success will be persuading a handful of Labour MPs to defy their party’s leadership and vote for the deal. Labour Leader Jeremy Corbyn has urged his MPs to stand firm and oppose the agreement, and there have been dire warnings from some party executives that rebels could lose their nomination to stand in the next election. That may not be enough to dissuade several Labour MPs who represent ridings in northern England, where Brexit is popular. Around 17 have indicated in recent weeks that they would support a deal under some circumstances. It’s not clear how many of them will be prepared to side with Mr. Johnson on Saturday, but one Labour MP, John Mann, said on Friday that the figure was close to a dozen.
“It could well be that tomorrow’s result will hinge on how the relevant Labour MPs who are inclined to vote for a deal interpret the signals from their leadership," said Rob Ford, a professor of politics at the University of Manchester.
Dr. Ford added that Mr. Johnson could still gain politically even if he loses the vote. Under a law passed by MPs last month, the Prime Minister would have to ask the EU for an extension to the Oct. 31 deadline.
If Mr. Johnson is forced to ask for an extension and then calls a snap election, Dr. Ford said he’ll be able to blame Parliament for delaying Brexit and prolonging the debate. “The politics of the extension become less bad for him because he has a really clear and easy to understand argument for why it isn’t his fault,” he said.
“If he’s waving a great big thick sheaf of paper and saying ‘This is the agreement they won’t vote for,’ people can understand that. That’s why getting this deal agreed with the EU was such a big, big win for him because politically he’s got the upper hand in terms of spinning the outcome [on Saturday].”