LONDON (CBS) -- British Prime Minister Theresa May's gamble in calling an early election backfired spectacularly, as her Conservative Party lost its majority in Parliament and pressure mounted on her Friday to resign. But British media were reporting that May wouldn't step aside.

The stunning result throws British politics into chaos and could send Britain's negotiations to leave the European Union - due to start June 19 - into disarray. The British pound lost more than 2 cents against the dollar in initial trading as results became clear.

With 646 of 650 seats in the House of Commons declared, the Conservatives had 315 to the Labour Party's 261. Even if the Conservatives won all the remaining seats, the party would fall short of the 326 needed for an outright majority. Before the election, the Conservatives had 330 seats and Labour 229.

Guenther Oettinger, a German member of the European Commission, said Friday that the election result had left it unclear whether negotiations between the U.K. and Europe on Britain's exit from the EU could be launched on June 19 as planned. The EU was hoping for a stable British government to help ensure smooth divorce negotiations ahead of Britain's departure in March 2019. 

"We need a government that can act," Oettinger told radio station Deutschlandfunk, according to the Reuters news agency. "With a weak negotiating partner, there's the danger than the negotiations will turn out badly for both sides... I expect more uncertainty now." 

May called the snap election in the hope of increasing her majority and strengthening Britain's hand in exit talks with the European Union with a "strong and stable government." Instead, the result means the Conservatives will need to rely on support from smaller parties to govern, with more instability and the chance of yet another early election.

"This is a very bad moment for the Conservative Party, and we need to take stock," Conservative lawmaker Anna Soubry said. "And our leader needs to take stock as well."

The results confounded those who said Labour's left-wing leader, Jeremy Corbyn, was electorally toxic. Written off by many pollsters, Labour surged in the final weeks of the campaign. It drew strong support from young people, who appeared to have turned out to vote in bigger-than-expected numbers.

Corbyn called for May to quit, saying, "The Prime Minister called the election because she wanted a mandate. Well the mandate she's got is lost Conservative seats, lost votes, lost support and lost confidence. I would think that's enough, to go, actually, and make way for a government that will be truly representative of all of the people of this country."

Speaking after being re-elected to his London seat, Corbyn said the election result means "politics has changed" and voters have rejected Conservative austerity.  

As she was resoundingly re-elected to her Maidenhead seat in southern England, May looked tense and did not spell out what she planned to do.

"The country needs a period of stability, and whatever the results are the Conservative Party will ensure we fulfil our duty in ensuring that stability," she said.

Many predicted she would soon be gone.

"Clearly, if she's got a worse result than two years ago and is almost unable to form a government, then she, I doubt, will survive in the long term as Conservative Party leader," former Conservative Treasury chief George Osborne said on ITV.

The result was bad news for the Scottish National Party, which lost about 20 of its 54 seats. Among the casualties was Alex Salmond, a former first minister of Scotland and one of the party's highest-profile lawmakers.

The losses complicate the SNP's plans to push for a new referendum on Scottish independence as Britain prepares to leave the EU. Scottish Conservative leader Ruth Davidson said the idea of a new independence referendum "is dead. That's what we have seen tonight."

May had hoped the election would focus on Brexit, but that never happened, as both the Conservatives and Labour said they would respect voters' wishes and go through with the divorce.

May, who went into the election with a reputation for quiet competence, was criticized for a lackluster campaigning style 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.

Then, attacks that killed 30 people in Manchester and London twice brought the campaign to a halt, sent a wave of anxiety through Britain and forced May to defend the government's record on fighting terrorism. Corbyn accused the Conservatives of undermining Britain's security by cutting the number of police on the streets.

Eight people were killed near London Bridge on Saturday when three men drove a van into pedestrians and then stabbed revelers in an area filled with bars and restaurants. Two weeks earlier, a suicide bomber killed 22 people as they were leaving an Ariana Grande concert in Manchester.

Rachel Sheard, who cast her vote near the site of the London Bridge attack, said the election certainly wasn't about Brexit.

"I don't think that's in the hearts and minds of Londoners at the minute, (not) nearly as much as security is," said Sheard, 22. "It was very scary on Saturday."

Steven Fielding, a professor of politics at the University of Nottingham, said Britain had seen an election "in which the personal authority of a party leader has disappeared in an unprecedented way."

"If she had got the majority she wanted, she would have been a supreme political colossus," he said. "She did not get that and she's a hugely diminished figure. She's a zombie prime minister."