Tim Bale, professor of politics at Queen Mary University of London, said a strong result for Farage’s party on Thursday might scare both Labour and the Conservatives into toughening their stance on immigration and other issues to try to “become Reform-light.” He said that would be a mistake.

The populist politician’s Reform UK party is soaring in the polls—and doing better at the ballot box—as voters lose patience with slow economic growth and high immigration.