Two parties have dominated British politics since the end of the First World War. The Labour Party, currently led by veteran left-winger Jeremy Corbyn, and the ruling Conservative Party, which—for the next few weeks, at least—is led by disastrous outgoing Prime Minister Theresa May.

Imagine the shock over morning cups of tea, then, caused by an earth-shattering poll published Friday that showed those two parties lodged in third and fourth place. That is to say, if the poll is correct, a British general election would leave neither the Conservatives nor Labour anywhere near forming the next government.

So, what the Hell is going on? In a word: Brexit. The ongoing catastrophe that is paralyzing Britain’s political class has changed how voters think and feel about politics and there appears to be no going back. In second place in the poll was Nigel Farage’s Brexit Party, which, last week, was by far the most supported group in the EU parliamentary elections.

At the top of the poll was a party equally evangelic about its Brexit position—but on the opposite side of the debate. The Liberal Democrats, which ran the European election campaign with the frank and very British slogan “Bollocks to Brexit,” could win an election if it was held today.

Founded in the late 1980s as a merger of the ancient Liberal Party and the short-lived Social Democratic Party, the Liberal Democrats have never really been a major player.

Through the 1990s and 2000s, it was a refuge for voters who found Labour and the Conservatives unpalatable. The perennial “third party” in parliament, it was an inoffensive minor force who was praised for its opposition to the Iraq War and campaigned on important but ultimately not particularly interesting issues such as electoral reform.

That changed under the leadership of Nick Clegg—now better known in the U.S. as Facebook’s vice president for global affairs.

A few years after he took over, Clegg starred in the 2010 general-election campaign TV debates in a phenomenon dubbed by cringe-inducing pundits as “Cleggmania.” Clegg’s popularity put the Lib Dems in the strong position to form a coalition government with David Cameron’s Conservatives.

But, while Clegg still insists the Lib Dems were a moderating force on the center-right Conservatives—and, given events since, he may have a point—the coalition proved disastrous for the party. After winning a lot of support from young people, and posing with a pledge not to introduce university fees, that’s exactly what the Clegg/Cameron government did.

The anger provoked by that betrayal, and by the party being linked to Cameron’s harsh program of public spending cuts, saw the party decimated at the next general election in 2015. It went from having 57 seats in the House of Commons to a pathetic eight, forcing the perennial third largest party into fourth place behind the Scottish National Party.

Between now and then, there has been nothing but misery.

Despite constant talk of a chirpy #LibDemFightback, the party has spent four years in the political wilderness as voters punished them for the coalition. They gained a couple of MPs in 2017 snap general election, but leader Tim Farron stepped down after repeated criticism over his refusal to say whether he thought that homosexual sex was or wasn’t a sin.

Enter current leader Vince Cable, a 76-year-old party veteran who was seen as an unexciting but reliable short-term leader to give the party time to work out what it was going to do. For two years, he seemed doomed to fail and decided earlier this year that he’d had enough and would soon leave.

But then something remarkable happened very quickly. After unveiling its “Bollocks to Brexit” slogan, the party saw its poll ratings for the European elections surge until they reached second behind the Brexit Party. And so it came to pass—results showed the Lib Dems came in second with over 20 percent of the vote, marking the end of its wilderness years.

Often, voting intention in European elections doesn’t overlap with voting intention in a British parliament because voters focus on different issues. But, in the poll released Friday, the Lib Dems were out in front with 24 percent of the support, the Brexit Party had 22 percent, and the two main parties languished behind in joint third place with 19 percent of the voting intention.

So, what’s going on here? First, Brits seem to love a sweary slogan. But, more fundamentally, it’s showing how referendums with two choices polarize voters, and they choose parties that reflect that. “We did spectacularly well in the European elections because we had a very clear, simple message on Brexit,” Lib Dem leader Cable told The Daily Beast.

After Theresa May failed to deliver Brexit as promised, and negotiated a deal that many anti-EU voters didn’t believe counted as Brexit at all, pro-Brexit voters fled to the clearer and more hardline position of the Brexit Party.

And, as Jeremy Corbyn tried to ride two horses at once by adopting a muddy position designed not to alienate Remain or Leave voters, both deserted him. The Lib Dems picked up support from pro-Europe Labour backers, and the Brexit Party hoovered up voters who want to get on with leaving.

Former leader Farron told The Daily Beast the party was “heavily punished” after the coalition government, but added: “Our rebuilding at local level and our adopting of a clear and principled position opposing Brexit has led to the Lib Dems gaining electoral success in this year’s elections as moderates from Labour and Conservatives leave their parties and switch to the Lib Dems.”

The exact same phenomenon happened in Scotland after its referendum on independence in 2014. Voters chose a side during that vote, and didn’t just stop believing in it after those ballots were counted. Subsequent elections saw a huge rise in support for the pro-independence party, the SNP, and the clear pro-union party, the Scottish Conservatives.

When voters are forced to make a decision in a climactic and emotional referendum with so much as stake, they become entrenched in that position and parties without a clear position just get lost in the fight.

The Lib Dems won’t get carried away. They topped one poll in 2010 under Clegg and quickly slipped back.

Cable said it would be “very difficult” for the party to form the next government “but given the extreme fragility of the British political system at the moment and the fact two major parties are both in a state of civil war anything could happen.”

But it won’t be Cable leading the party on to new successes. He’s due to make way for a new leader in the coming months. Does he regret his announcement to leave now that the party is back from the dead? “In public life, you have to make these kind of big decisions clearly and stick with them,” he said. “I made a commitment three months ago publicly that I would be going by the summer and that I would still be active in political life, so it’s not that I’m just disappearing to Antarctica or somewhere.”

Make no mistake, Brexit is a paradigm-shifting crisis.

Labour has to convince voters it’s a Remain party or the Lib Dem surge will not simply ebb away. The same is true of the Conservatives, whose support will stay with Farage if it doesn’t own Brexit.

If they both fail, then they both face a painful, simultaneous death.