Britain is heading for an election on Dec. 12 and it will now be up to voters to try and resolve the Brexit conundrum that has bedevilled the country for more than three years.

This will be the first December election in Britain in nearly 100 years and it’s expected to be one of the most divisive campaigns in generations, dominated by how to get the country out of the European Union. “I think it’s going to be one of the nastiest, most brutal elections we’ve seen in our lifetime,” Labour MP David Lammy told a group of foreign journalists on Tuesday. “I don’t think it will resolve anything.”

Experts say Brexit has changed the political landscape and shattered long-held party allegiances, making the outcome almost impossible to predict. Prime Minister Boris Johnson’s Conservatives and Jeremy Corbyn’s Labour Party are expected to lose dozens of seats to third parties, which means the result could be another hung Parliament and more Brexit deadlock.

“Britain is now set for the most consequential election in its entire postwar history,” said Matthew Goodwin, professor of politics at the University of Kent. “The election will determine the future of Boris Johnson’s embryonic premiership, Jeremy Corbyn’s economically radical Labour Party, whether Britain ever holds a second referendum [on Brexit] and, of course, Brexit.”

Mr. Johnson had been pushing for an election for weeks, hoping to cash in on a Brexit deal he recently struck with the EU and prove to voters that only his party can deliver Brexit. He’d been stymied by a law that requires two-thirds of MPs to consent to moving the election forward from the fixed date of May 5, 2022. He finally succeeded on Tuesday when Mr. Corbyn dropped Labour’s objection to an early vote.

Mr. Corbyn said he agreed after the EU said on Monday it would extend the deadline for Britain to leave the bloc to Jan. 31, 2020, from Oct. 31. That removed the possibility of Britain departing without a deal on Halloween, he said. With Labour’s backing, MPs voted overwhelmingly to approve an election on Dec. 12.

The election carries risks for Mr. Johnson. The Conservatives have been leading most opinion polls and Mr. Johnson is a charismatic leader, unlike his predecessor, Theresa May, who blew an even larger lead in the polls in 2017 and nearly lost that election to Labour.

Mr. Johnson also has a Brexit deal he can sell to the electorate and he’ll blame the opposition for blocking what a majority of people voted for in the 2016 referendum, when 52 per cent supported leaving the EU. Nonetheless, the Tories are expected to lose seats in Scotland and London, where Brexit is unpopular. The party hopes to make up those losses by taking Labour seats in Northern England and the Midlands, where support for Brexit is strong.

Mr. Johnson will also have to contend with the Brexit Party, launched last spring by Nigel Farage, who favours leaving the EU without a deal. Mr. Farage has been highly critical of Mr. Johnson’s Brexit deal and he has lambasted the Prime Minister for failing to get Britain out of the EU on Oct. 31, as he repeatedly promised. While the Brexit Party has been falling in most opinion polls, its votes could make a difference in close races.

“Boris Johnson is currently enjoying large poll leads, but we should remember that this is also the most volatile electorate in British history,” Dr. Goodwin said. “In short, only a fool would make a confident prediction.”

Sir John Curtice, professor of politics at Glasgow-based Strathclyde University, said other parties could win more than 100 of the 650 seats at stake. “This is an asymmetric election,” he told LBC radio. “It’s an election that Boris Johnson has to win. If he does not get a majority or something very very close to it, he will almost undoubtedly not be able to stay in government because the Conservatives do not have any friends [among the other parties].”

Mr. Corbyn, too, faces challenges. Labour has been slumping in most polls and Mr. Corbyn’s leadership has come into question. The party’s position on Brexit – vowing to strike a new deal with the EU, put it to a referendum and then campaign to remain in the bloc – has also been muddled.

On Tuesday, several Labour MPs openly questioned Mr. Corbyn’s willingness to go to the polls, with one MP, Barry Sheerman, calling the move “sheer madness.” Mr. Corbyn remained steadfast, telling reporters on Tuesday, “I have consistently said that we are ready for an election and our support is subject to no-deal Brexit being off the table. We will now launch the most ambitious and radical campaign for real change our country has ever seen.”

Labour also faces a threat from the resurgent Liberal Democrats, who have promised to scrap Brexit altogether and keep Britain in the EU. That stance could make the party a viable alternative to voters who don’t want Brexit and can’t understand Labour’s position.

The Globe and Mail, October 28, 2019