Zohran Mamdani, a little-known state lawmaker whose progressive economic platform electrified younger voters, surged into the lead in the Democratic primary for mayor of New York City, putting him on the verge of a stunning upset.
Former Gov. Andrew M. Cuomo, who had led the race for months, conceded the primary and congratulated Mr. Mamdani, a 33-year-old democratic socialist, in remarks after 10 p.m. He did not rule out running in the fall’s general election on a third-party ballot line.
“Tonight was not our night,” a deflated-looking Mr. Cuomo, 67, told supporters. He added, of Mr. Mamdani: “Tonight is his night. He deserved it. He won.”
Unless one candidate receives more than 50 percent of first-choice votes in the initial count under the city’s ranked-choice voting system, counting will continue next week.
At a moment when Democrats are searching for an answer to President Trump, Mr. Mamdani ran on an unabashedly progressive agenda, promising to make buses free, freeze the rent on rent-stabilized apartments and raise taxes on the wealthiest New Yorkers. His promise of generational change appears to have resonated with large numbers of voters.