Exit polling showed Prime Minister Theresa May’s governing Conservatives losing their parliamentary majority despite staying as the largest party, while Labour boosted its position with a far better performance than expected, in Britain’s general elections Thursday night.

The sensational findings, which came as voting ended but before any ballots had been tallied, put May’s continued rule into question, despite surveys in previous days predicting she would hold onto her seat as prime minister.

The poll showed the Conservatives falling to 314 seats from 330, and the Jeremy Corbyn-led Labour party jumping to 266 seats from 220 in the 650-member parliament, while the SNP (Scottish National Party) fell to 34 and the Lib Dems jumped to 14 seats. Other parties mustered 22 seats between them.

Those figures, if proven accurate, would give Britain a “hung parliament,” leaving the governing Conservatives 12 seats short of the 326 seats needed for an overall majority.

A 20-seat swing in either direction from the exit polling figures could determine whether May or Corbyn will lead the country forward.

The exit polling was based on questions put to some 30,000 voters. Such polls have been fairly accurate in the past three British elections.

Voters were choosing the 650 lawmakers for the House of Commons after Prime Minister May called the vote three years early, hoping to boost her majority before starting Brexit negotiations. But a series of attacks forced her to defend the government’s record on terrorism, and she has promised to crack down on extremism if she wins.

“I think we’re on the verge of a great result,” said Emily Thornberry, Labour’s candidate for foreign minister, soon after the exit poll was published and within minutes of the polling stations closing. If the exit poll proved accurate, she said, May “should go… She has manifestly failed.”

“It’s still very, very early in the evening,” countered the Conservatives’ Northern Ireland Secretary James Brokenshire. “It’s too early in the night to be drawing conclusions.”

Counting got under way at 10 p.m. British-time, and was continuing through the night.

The pound immediately tumbled after the poll. The British currency was trading at $1.2751, down 1.5 percent from the day-before level.

When May called the election seven weeks ago, she was seeking to capitalize on opinion polls showing that the Conservatives had a wide lead over the opposition Labour Party. At that moment, the time seemed right.

May became prime minister through a Conservative Party leadership contest when predecessor David Cameron resigned after the referendum in which Britain voted to leave the European Union. She went into the election untested on a national campaign, but with a reputation for quiet competence. She championed “strong and stable government.”

May was criticized for a lackluster campaign and for a plan to force elderly people to pay more for their care, a proposal her opponents dubbed the “dementia tax.” As the polls suggested a tightening race, pollsters spoke less often of a landslide and raised the possibility that May’s majority would be eroded.

After the terror attacks in Manchester and London, which killed 30 people and forced the suspension of campaigning, security became the focus of the debate.

In her final message to voters, May appealed directly to the undecided, urging them to support her in negotiating the best deal for Britain as it leaves the European Union.

“I can only build that better country and get the right deal in Brussels with the support of the British people,” she said. “So whoever you have voted for in the past, if that is the future you want then vote Conservative today and we can all go forward together.”