The president, who has a history of spewing sometimes vile insults at rivals, has in recent days escalated his attacks against the 33-year-old self-described democratic socialist. Trump has threatened to arrest Mamdani, to deport him and even to take over the country’s largest city if he wins the general election in November.

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

Zohran Mamdani has won New York City’s Democratic mayoral primary. A new vote count Tuesday under the city’s ranked choice voting system confirmed the progressive legislator’s stunning upset of former Gov.