Zohran Mamdani, the official Democratic nominee for New York City mayor, ran his campaign largely on affordability, placing the New York City housing crisis at the center of his platform.

Mr. Mamdani’s victory upended city politics and reverberated nationally. He relied on a memorable message, charisma and a strong ground game.

The New York City Election board on Tuesday confirmed a stunning victory by mayoral candidate Zohran Mamdani in the Democratic primary, clearing the way for the political upstart to be the party's nominee for the November mayoral election.