Jeremy Corbyn’s Labour Party received more votes than in any election for decades, outperforming expectations in a snap contest that an overly confident Conservative Prime Minister Theresa May herself called. Rather than gaining seats, May’s party lost about a dozen and is now trying to form a coalition government with the Democratic Unionist Party. Although final figures are not yet in, pollsters estimate that this outcome was the result of a surge of youth turnout that reached almost 70 percent.

These results come after years of predictions from both sides of the Atlantic that Corbyn’s leadership of Labour would relegate it to a fringe party and destroy its electoral prospects.

Tom Peck, a political correspondent for The Independent, wrote in 2016 that Corbyn “will lead Labour to electoral oblivion. Of that there is no doubt.” J.K. Rowling, the prominent author of the Harry Potter series of novels, predicted last year that Corbyn would bring about “the destruction of the Labour Party.”

Popular columnist Nick Cohen predicted that “Corbyn’s Labour won’t just lose. It’ll be slaughtered.” Piers Morgan even predicted the Conservatives would win a “90-100 seat majority.”

Opposition also came from senior members of Corbyn’s own party. “Jeremy’s personal ratings are the worst of any opposition leader on record — and the Labour party is suffering badly as a result,” complained Sadiq Khan, the mayor of London, as he supported a challenger to Corbyn’s leadership last year.

Owen Smith, who challenged Corbyn for leadership in 2016, repeatedly argued that Corbyn’s Labour Party would be essentially a social movement that could not gain power. “We are a Labour government in waiting, not a protest movement,” he lectured Corbyn during a debate.

Zack Beauchamp of Vox.com, a popular political website in the United States, used Corbyn as an example of why left-wing economic policy supposedly can’t stop right-wing populism. “Take Britain’s Labour Party, which swung to the populist left by electing Jeremy Corbyn, a socialist who has proposed renationalizing Britain’s rail system, as its leader in 2015,” Beauchamp wrote earlier this year. “The results have been disastrous: the Brexit vote in favor of leaving the European Union, plummeting poll numbers for both Corbyn and his party, and a British political scene that is shifting notably to the right on issues of immigration and multiculturalism.”

Media Matters’s Eric Boehlert warned that “Corbyn’s been a disaster for Labour” this past January.

American Federation of Teachers president Randi Weingarten tweeted out a Washington Post article claiming that Corbyn’s ascendance would result in a worse result than 2015, when the Conservatives won a clear majority over Labour. “Lessons to be learned…” she added.

One-time Obama senior adviser David Axelrod said in an interview with the former president that the “Labor Party just sort of disintegrated in the face of their [2015] defeat and move so far left that it’s, you know, in a very — in a very frail state,” calling the process “Corbynization.” Obama seemed to agree with assessment, saying that “the Democratic Party has stayed pretty grounded in fact and reality.” Contrasting Bernie Sanders to Corbyn, Obama assured Axelrod that the same process wouldn’t happen in the United States because “Bernie Sanders is a pretty centrist politician relative to Corbyn or relative to some of the Republicans.”

Labour’s stronger-than-predicted performance appears to validate Corbyn’s thesis that a populist platform and an outsider leader would boost voter turnout and make the party more viable, not less. Or it at least proves that his approach is no disaster.

Cathy Newman of the U.K.’s Channel 4 News summarized the feeling among British pundits: