LONDON — Britain is on the brink of massive change. Unless the polls are spectacularly wrong, the center-left Labour Party will sweep into power Friday, ending 14 years of Conservative Party rule.

Prime Minister Rishi Sunak didn’t need to call an election before the end of the year, but he decided to gamble, hoping that the polls would narrow. They haven’t, really. The Conservatives are deeply unpopular. Voters don’t trust them to handle the economy, one of the party’s traditional strong points. The voters are upset about soaring costs, high interest rates, stagnant wages and overwhelmed public services. A tetchy mob is hungry for change, even if it is unclear what that means. Some polls predict that Labour could win bigger under its leader, Keir Starmer, than it did during Tony Blair’s landslide victory for the party in 1997.