How Zohran Mamdani Stunned New York and Won the Primary for Mayor

On a frigid night in January, Zohran Mamdani, a little-known state lawmaker running for mayor, climbed into a halal cart in Manhattan’s Zuccotti Park for a plate of chicken and rice.

With cameras rolling, the fresh-faced Democrat mainlined a takeout container as he explained in simple terms how the city’s arcane permitting process was squeezing vendors and driving “halalflation.”

The 90-second video went viral, but it also offered a more direct sign of Mr. Mamdani’s growing reach. Mahmoud Mousa, the Egyptian-born vendor next to him onscreen, said that his Brooklyn neighbors, friends and family inundated him with questions about the 33-year-old candidate in a suit and tie.

“Politicians never care about the problems we have,” he said in an interview last week. “But he is saying he is going to take care of how I live.”

Five months later, the episode illustrates how Mr. Mamdani, a democratic socialist, broke New York’s political mold and pulled off a seismic upset to claim the Democratic nomination for mayor over far more seasoned rivals, including former Gov. Andrew M. Cuomo.

The victory sent shock waves through American politics, electrifying progressives, alarming some party leaders and handing Republicans fresh fodder to attack Democrats. It also set the stage for a pitched general election battle against Mayor Eric Adams, as Mr. Mamdani now confronts an antagonistic business class and many Jewish New Yorkers alarmed by his stark criticism of Israel’s war in Gaza.