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

President Trump called for Mamdani’s arrest and deportation, DHS Homeland Security Secretary Kristi Noem declared the agency had “authorities it has never utilized before.”

Zohran Mamdani's New York mayoral primary prompted a variety of reactions among the city's Democrats, with some vowing to oppose him and others offering support.