LONDON — British voters defied the will of their leaders and international allies by cutting ties with the European Union in a stunning result Friday that threw financial markets into turmoil and forced Britain’s prime minister to resign.
As Britain absorbed the ground-breaking news, the political fallout reached to the highest level with Prime Minister David Cameron saying he would step down after championing the campaign to remain in the European Union.
Cameron said the country now deserved “fresh leadership” in the face of the rejection he and the supporters of the “remain” campaign suffered in Thursday’s referendum.
Cameron, who enjoys a close relationship with President Obama, said he hoped a new prime minister could be in place by October.
He said that only after the transition in leadership would the country begin the formal process of withdrawing the nation from the European Union. By the time the outcome was clear, the pound had already plummeted to its lowest level against the dollar in decades, and stock markets dropped sharply around the world.
In his comments, Cameron sought to offer reassurances to jittery markets, calling Britain’s economy is “fundamentally sound” and said there would be no immediate changes in the status of immigrants in the country. But his decision only added to the uncertainty that descended suddenly overnight.
The vote is perhaps the most dramatic to date in a wave of populist and nationalist uprisings occurring on both sides of the Atlantic that are overturning traditional notions of what is politically possible.
The vote will have a profound effect on the E.U., which will lose a major military and diplomatic power. “This looks to be a sad day for Europe and for Britain,” said Germany’s foreign minister, Frank-Walter Steinmeier.
For months, Britain’s political and economic elite had looked on with growing apprehension as the country flirted with a choice — popularly known as Brexit — thatexperts had warned could lead to global recession and a rip in the Western alliance. The vote could also lead toScottish secession and a broader E.U. unraveling.
But most analysts had predicted this pragmatically minded country would ultimately back away from the move, and opt to keep Britain in an organization regarded as a pillar of the global economic and political order.
Instead, a majority of British voters heeded the call of pro-Brexit campaigners to liberate the nation from what many here regard as an oppressive Brussels bureaucracy that enables mass migration into the country.
“Let June the 23rd go down in our history as our independence day!” cried a jubilant Nigel Farage, a firebrand anti-E.U. leader, in a 4 a.m. celebration. All around him, “leave” campaigners clinked pints of beer and cheered their improbable victory.
When polls closed six hours earlier, Farage had all but conceded defeat, saying he believed “remain” had won. But as results poured in through Thursday night and into the early hours of Friday, the “remain” camp was increasingly despairing.
About a third of results had yet to be counted as of 4 a.m. local time. But the BBC reported that “leave” had taken an insurmountable lead.
The results came after 15 hours of voting, from the remote Scottish isles to the tip of Gibraltar. The outcome revealed vast divides — with massive victory margins for “remain” in thriving metropolitan centers such as London and equally resounding victories for “leave” in small towns, rural areas and struggling, post-industrial cities.