Britain’s political forecast calls for turmoil, Brexit pressure

LONDON — Britain is getting a new prime minister. Buckle up for a rocky ride.

On Tuesday, the U.K.’s governing Conservatives will announce the winner of a contest to replace Theresa May as leader of the party and the country. Just over three months later, on Oct. 31, Britain is scheduled to leave the European Union.

With the new British leader on a collision course with both the EU and Britain’s Parliament over Brexit, the U.K. could be heading for a political crisis, a recession, an election, a referendum — or several of those options at the same time.

“It’s a very fluid situation,” said Nick Wright, an expert on EU politics at University College London. “Literally, anything could happen.”

Barring a major upset, Britain’s next prime minister will be Boris Johnson. The buoyant former foreign secretary is so far ahead with pollsters that it will be a huge shock if rival Jeremy Hunt is declared the victor on Tuesday.

Johnson, who sometimes has an ambiguous relationship with facts, campaigned with characteristic bluster, vowing to revive the country’s “mojo” and making one main promise: Britain will leave the EU on Oct. 31, “come what may.”

He may find that promise hard to keep. The new leader heads a government with no parliamentary majority in a deeply divided country that is facing off with a mistrustful EU.

The prime minister is due to take office Wednesday, but the new leader could face a challenge before he’s even had a chance to unpack. The opposition Labor Party is considering calling a no-confidence vote in the Conservative government on Thursday. It would only take a handful of Conservative rebels to defeat the government and — unless it can overturn that vote within 14 days — trigger an early election.

Both Johnson and Hunt...