LONDON — Supporters of a British exit from the European Union opened up a substantial lead over advocates of staying in the bloc as the nation tallied the votes early Friday on one of its most momentous decisions in generations.

With more than half of towns and cities reporting, the so-called Leave campaign was leading by more than 700,000 votes out of more than 24 million that had been counted, an advantage of 51.6 percent to 48.4 percent over the Remain campaign, according to the BBC.

“Dare to dream that the dawn is breaking on an independent United Kingdom,” Nigel Farage, the leader of the U.K. Independence Party, one of the primary forces behind the push for a referendum on leaving the European Union, told cheering supporters just after 4 a.m., denouncing the “lies, corruption and deceit” that he said elites in both major parties — Conservative and Labour — had peddled.