Ten-year-old Bug, sits on her father’s shoulders during the People’s Vote Rally on October 19, 2019 in London. Photo: Kiran Ridley/Getty Images

The U.K. House of Commons voted on Tuesday to hold an election on December 12, passing Prime Minister Boris Johnson’s fourth attempt at calling a snap poll and setting the stage for a high-stakes campaign centered on whether and how the long national drama of Brexit will finally end.

MPs approved Johnson’s election bill overwhelmingly, 438 to 20, but many opposition lawmakers abstained, including the Liberal Democrats, the Scottish National Party, and over 100 Labour MPs. The bill will now go to the House of Lords for final approval and will likely become law by the end of the week. Parliament will dissolve next Wednesday for a historically consequential election campaign lasting just five weeks. (Imagine that!)

This will be the first time the U.K. has held an election in December in nearly a century: The country generally avoids voting in the dead of winter as the short days and cold weather make for miserable campaigning. Yet with an E.U. “flextension” of the Brexit deadline until January 31 hanging over their heads, U.K. politicians are under time pressure to agree on a deal. Last week, MPs approved Johnson’s withdrawal agreement in principle but rejected his three-day timetable for debating and voting on the full bill, leading the prime minister to put the bill on hold and press for a new election.

Johnson, who had said he’d rather “die in a ditch” than not deliver Brexit by the previous deadline of October 31, was forced by Parliament to request the extension nonetheless. He has blamed the delay on lawmakers’ intransigence and argued that the only way to break the Brexit impasse is to elect a new Parliament — ideally one with a Conservative majority that will pass his deal without amending it beyond recognition. Early elections require a two-thirds supermajority in the Commons, and Labour had rejected Johnson’s earlier attempts to call a snap poll, to make sure that the Brexit extension was in place before dissolving Parliament.

The contours of the campaign are already taking shape, with the key parties aligned around their positions on Brexit. Johnson said it was time to “come together to get Brexit done” and readmitted 10 of the 21 Conservative MPs he had expelled from the party for defying him over Brexit last month, in an attempt to begin restoring party unity. “Let’s get Brexit done” will be the crux of the Tories’ platform, with Johnson stumping for his deal while decrying the obstructionism of Establishment elites (this coming from a man who studied classics at Oxford and went on to edit the Spectator as his stepping stone to a career in Conservative politics).

However inauthentic this populist message may be, the Tories hope it will resonate with voters in pro-Leave constituencies currently represented by Labour MPs, angry that their government has failed to deliver what they voted for more than three years ago. These seats represent their best hope of reassembling their majority. The Tories must also contend, however, with a new rival on the far right: Nigel Farage’s newly established Brexit Party, which is expected to field candidates for most if not all of the Commons’ 650 seats.

Farage’s party, representing those arch-Brexiteers for whom even Johnson’s deal is too soft, is pushing for a no-deal Brexit. The Tories are begging the Brexit Party not to run candidates in places where they might risk splitting the right-wing vote and losing to Labour, but the new party is aiming for as many as 50 seats, targeting English heartland constituencies with Labour MPs. The Brexit Party is also looking to ally with the Democratic Unionist Party of Northern Ireland to form a hard-Brexit bloc that a Conservative government would need to court to form a working majority. The DUP has managed to block two Brexit deals despite holding just ten seats, so Farage knows he can wield considerable influence in this environment even if his party wins only a handful of the races they contest.

Labour, meanwhile, will be the one party campaigning on something other than Brexit. The left-wing party is proposing to negotiate a softer deal that keeps the U.K. largely aligned with the E.U. on trade, labour, and environmental regulations, then hold another referendum on whether to leave with that deal or cancel Brexit altogether and remain in the E.U. Johnson will spin that plan as overly complicated and indefinitely extending the current state of uncertainty and legislative quagmire. Labour leader Jeremy Corbyn would much rather talk about his ambitious policy platform, a 21st-century socialist agenda that would make Bernie Sanders blush: re-nationalizing railways and utilities, mandating employee representation on corporate boards of directors, and raising taxes on the wealthy to pay for free college and a Green New Deal.

Like the Conservatives, Labour will find itself squeezed on both flanks. Those MPs with pro-Brexit constituents will have to persuade those voters that the Johnson deal is bad enough to reject — though a leaked document revealing that his government might diverge from E.U. standards on regulation and workers’ rights after Brexit could help them make that case. Remain voters will be courted by the Liberal Democrats, who are campaigning on a promise to cancel Brexit.

In Scotland, the pro-E.U. Scottish National Party will mainly be focused on winning back the seats they lost to the Conservatives in 2017. The SNP has already captured much of the left-wing vote in Scotland, leaving Labour with only a few seats there, and would likely join a Labour-led government pledging a second referendum on Brexit — but would also seek another vote on Scottish independence, which could well pass.

Johnson hopes that this election will give him a Conservative majority and a mandate to enact his Brexit deal, but that’s just what his predecessor Theresa May hoped for when she called the last vote in 2017, only to end up with a hung Parliament and a crippling dependency on the DUP. Current polling shows the Conservatives with a roughly ten-point lead over Labour; if those numbers hold, the Tories have a good chance of winning a majority in December. A lot can happen in five weeks, however, and even a slight shift toward Labour could give them a plurality, though an outright majority will be very hard to achieve. Given how intensely polarizing the Brexit debate has been for the U.K., an election that is effectively a referendum on Brexit could produce a closely divided outcome, especially with so many third-party wild cards in play.

Even if Johnson gets everything he wants and a new Conservative majority comes into power, a huge segment of the British public will still be deeply unhappy with his version of Brexit. Johnson’s deal is expected to take a toll on the U.K. economy, lowering per capita GDP by as much as 7 percent over the next decade. The heretofore abstract economic sacrifice of Brexit will finally become real and tangible. Citizens of the U.K. will finally get to see what 52 percent of them voted for in 2016 — and even those who voted for it might not like it.

Besides the economic impact, Brexit has already made an indelible mark on the British body politic. In December 2015, Sam Knight points out in a New Yorker feature this week, “about one per cent of British people believed that Britain’s membership in the European Union was the most important issue facing the country.” Since then, it has somehow become the defining issue of a generation, shaping entire political identities, bitterly dividing the country, and tying up the government in intractable debate for years. Whatever happens in the next few months, the ramifications of Brexit will be felt for many years to come.