The pulsing beat of a dance track grew to a thunderous pitch and the crowd rose to its feet. Beams of light flashed across the cavernous arena in Birmingham, central England. Then, at last, Nigel Farage, the right-wing populist leader who claims he can fix a “broken Britain,” arrived onstage, hitching a ride on a backhoe.

Mr. Farage, who leads the anti-immigration party Reform U.K., has long been one of Britain’s most ardent supporters of President Trump. He has learned from the president’s campaign tactics, too.

That means, among other things, that the political rally is back in Britain.

In the weeks before municipal elections and a special election in England on May 1, Mr. Farage has been touring the country, taking to the stage in Cornwall, Darlington and Hull, smiling broadly, cracking jokes and railing against “illegal immigrants,” whom he promises to deport.

Since returning to the leadership of Reform last year and then being elected as a British lawmaker for the first time, Mr. Farage has led the insurgent party to an extraordinary surge in the polls. It won 14 percent of the vote last July, but now regularly polls at around 25 percent, overtaking the main opposition Conservatives and, in some surveys, the governing Labour Party.

Mr. Farage rode onto the stage at the rally on an excavator.Credit…Andrew Testa for The New York Times

Thursday’s elections, while limited in number, are the first test of Reform’s ability to convert that polling into power. Analysts expect the party to emerge with hundreds of municipal seats and two regional mayors. It’s also favored to win a closely fought special election for a parliamentary seat the same night.