Brexit Champion Says He’ll Run for Parliament, Jolting U.K. Election

Nigel Farage, the pro-Brexit campaigner and serial disrupter of British politics, announced plans on Monday to run as a candidate in Britain’s general election next month, dealing a new setback to the prospects of the country’s embattled prime minister, Rishi Sunak.

The surprise announcement from Mr. Farage, who represents an insurgent hard-right movement that campaigns to curb immigration, threatens to upend the campaign by taking votes from Britain’s governing Conservative Party. In doing so, he could make it even harder for Mr. Sunak and his party to narrow a double-digit gap in the polls with the opposition Labour Party.

Divisive, charismatic and famed for his communication skills, Mr. Farage was one of the architects of Brexit, which a slim majority of Britons supported in a 2016 referendum. An earlier decision by Mr. Farage not to run this year was thought by some analysts to have sapped momentum from his party, Reform U.K., the successor to the Brexit Party he once led.

Mr. Farage said last month that he would not seek a parliamentary seat because he wanted to prioritize supporting Donald J. Trump’s electoral campaign in the United States. Mr. Farage is a longtime ally of the former president and campaigned for him in 2016 and 2020.

But on Monday Mr. Farage reversed his decision, saying he would take over as leader of Reform U.K. for the next five years and run for a seat in Parliament.

“I’ve changed my mind — it’s allowed, you know,” he said. “I am going to stand in this election.” He added that he would run in Clacton, a seaside area where support for Brexit has been strong.

The announcement comes on the eve of one of the biggest events of Britain’s general election campaign so far: a televised debate on Tuesday night between Mr. Sunak and Keir Starmer, the leader of the opposition Labour Party.

Mr. Sunak is already under significant pressure, with his Conservative Party trailing badly in opinion polls and after a gaffe-prone start to the campaign.

The change of heart by Mr. Farage could worsen prospects for the prime minister because, according to analysts, Reform U.K. threatens to take a significant number of votes from the Conservatives. Until now, much of Mr. Sunak’s election strategy appeared to have been directed toward winning back potential supporters from Reform U.K., motivating his core right-wing voters to turn out and averting a big defeat.

But on Monday Mr. Farage claimed that the Conservatives were destined to be swept away on a wave of disdain for the political establishment and were “on the verge of total collapse.”

Despite Mr. Farage’s profile and popularity on the right of British politics, electoral success in Clacton, where he plans to run, is not guaranteed. He has never been elected to the British Parliament at Westminster despite seven previous attempts, although he was a member of the European Parliament for two decades before Britain quit the European Union.

Under Britain’s winner-take-all electoral system, candidates from smaller parties struggle because they need to secure the biggest share of the vote in the area they seek to represent.

Nonetheless, Mr. Farage appears to have calculated that he has a chance of victory in Clacton, a staunchly pro-Brexit town about 80 miles northeast of London. It was once represented by a lawmaker from the U.K. Independence Party, which Mr. Farage also once led and which campaigned for Britain to leave the European Union.

With the Conservatives trailing badly in the opinion polls, Mr. Farage has been increasingly vocal in predicting a significant defeat for Mr. Sunak’s party, even speculating that it could be on the scale of that suffered by Canada’s Progressive Conservatives in 1993.

In an interview with The Sunday Times of London over the weekend, Mr. Farage said that he had named his party Reform U.K. after the insurgent Canadian party of the same name.

“It took them time, it took them two elections, they became the biggest party on the center right. They then absorbed what was left of the Conservative Party into them and rebranded,” he said.

Asked if he was suggesting a merger between Reform U.K. and the Conservatives, Mr. Farage replied, “More like a takeover, dear boy.”

Mr. Farage has admirers on the right of the Conservative Party, including Jacob Rees-Mogg, a former cabinet minister who has even called for Mr. Farage to be invited to run as a lawmaker for the Conservatives.

Since 2016, Mr. Farage has been vocal in his support for Mr. Trump, and last week he described the convictions against him on 34 felony charges as a “disgrace.”

In the 2019 general election, the Brexit Party did not run candidates in many parliamentary constituencies. That was to help Boris Johnson, a former Conservative Party leader, whose election promise was that he would “get Brexit done,” and who won a big election victory.

But Richard Tice, Reform U.K.’s leader until Mr. Farage replaced him on Monday, has said there will be no repeat of that deal and has promised to fight the Tories across England, Scotland and Wales.