The outcome was not official, and even assuming Mr. Mamdani gains the nomination, he faces an unusually competitive general election in November.
Still, Mr. Mamdani declared victory at a rally early Wednesday in Queens, pledging to be a “mayor for every New Yorker” and framing his win as part of a movement powered by volunteers.
“Tonight we made history,” he said. “In the words of Nelson Mandela, it always seems impossible until it is done. My friends, we have done it.”
The decisiveness of New Yorkers’ swing toward Mr. Mamdani reverberated across the party and the country, at a time when Democrats nationally are searching for an answer to President Trump and are disillusioned with their own leaders.
Mr. Cuomo acknowledged his apparent defeat in a concession speech. “He won,” Mr. Cuomo told his supporters roughly 80 minutes after polls had closed and said he had congratulated Mr. Mamdani.
“Tonight was not our night,” he said, appearing deflated. “Tonight was Assemblyman Zohran Mamdani’s night.”
With 93 percent of the results in, Mr. Mamdani was the first choice of 43.5 percent of voters. Mr. Cuomo was in second place as the first choice of 36.4 percent of voters.
Mr. Mamdani said he would use his “power to reject Donald Trump’s fascism” and struck a note of unity after a contentious primary.
“Whether you voted for me, for Governor Cuomo or felt too disillusioned by a long broken political system to vote at all, I will fight for city that works for you,” he said. “That is affordable for you. That is safe for you. I will work to be a mayor you will be proud to call your own.”
The official outcome still awaits the tabulation next Tuesday of ranked choices under the city’s relatively new voting system. Mr. Cuomo, who has collected signatures to run on a third-party line in November, conspicuously did not vow to carry on his campaign in the general election.
“I wanted to look at the numbers and the ranked-choice voting to decide about what to do in the future, because I’m also on an independent line,” he said in an interview with The New York Times. “And that’s the decision.”
A candidate must clear 50 percent of the vote on primary night to be declared winner; the final result is not expected until July 1, when voters’ alternative choices are taken into account.
It is expected to be exceedingly difficult for Mr. Cuomo to narrow the gap in the ranked-choice elimination rounds. Several candidates encouraged their supporters to list Mr. Mamdani on their ballots and to leave Mr. Cuomo’s name off, as did the Working Families Party and other left-leaning groups.
Political strategists agreed with Mr. Cuomo that he could not overcome Mr. Mamdani’s lead.
“This is the biggest upset in modern New York City history,” said Trip Yang, a Democratic strategist.
The race had been volatile and bitter, with the two leading Democrats offering starkly different visions for the city and reflecting a generational divide in their party. Mr. Mamdani embodied energy and charisma, attracting droves of young, left-leaning New Yorkers; Mr. Cuomo represented the party’s older guard and ran a conservative rose-garden campaign, limiting his public appearances to churches and synagogues and supportive union halls.
“He won,” Mr. Cuomo told his supporters at a Primary Night party.Credit…Hiroko Masuike/The New York Times
The contest seemed to invigorate voters, with more than twice as many New Yorkers casting their ballots early in this year’s mayoral primary compared with the last mayoral primary in 2021, and high turnout on Primary Day that approached 1 million voters.
In his concession speech, Mr. Cuomo congratulated Mr. Mamdani for running “a great campaign.”
“He touched young people and inspired them and moved them and got them to come out and vote, and he really ran a highly impactful campaign,” Mr. Cuomo said. “I called him, I congratulated him. I applaud him sincerely for his effort.”
Mr. Mamdani and Mr. Cuomo, 67, both pledged to stand up to President Trump and to alleviate voters’ concerns over affordability and public safety. But they have diverged over how to accomplish those goals and fiercely attacked one another over their experience, character, donors and the conflict in the Middle East. Millions of dollars in negative television advertisement have filled the airwaves this month.
Mr. Mamdani’s left-leaning policies and open socialist affiliation would represent a sharp directional change for New York City, and some of his proposals would be likely to face opposition from Gov. Kathy Hochul and state lawmakers. Mr. Mamdani has proposed paying for his proposals, which also include freezing rent on rent-stabilized apartments and publicly financing vast amounts of new housing, by raising $10 billion in new revenue through taxes on businesses and the wealthy.
The race has captured national attention as a battle between the left wing of the Democratic Party and more traditional moderates. Mr. Mamdani, who would be the city’s first Muslim mayor and the youngest in a century, was endorsed by Senator Bernie Sanders of Vermont and Representative Alexandria Ocasio-Cortez of New York; Mr. Cuomo was endorsed by former President Bill Clinton and much of the local party establishment.
The former governor also benefited from a $30 million crush in outside spending from wealthy business interests, including former Mayor Michael R. Bloomberg, which buried Mr. Mamdani in attack ads. Mr. Mamdani, in contrast, had the highest number of individual donors in the race.
Mr. Cuomo, who resigned as governor in 2021 following allegations of sexual harassment that he denies, led in the polls for months. But Mr. Mamdani gained momentum with younger voters by focusing on a message that the city was unaffordable, spreading it through viral social media videos.
Brad Lander, the city comptroller, was in third place on Tuesday night with 11.3 percent; Adrienne Adams, the City Council speaker, was in fourth place with 4.1 percent.
Brad Lander, who cross-endorsed Mr. Mamdani, came in third in the race.Credit…James Estrin/The New York Times
If Mr. Mamdani wins the primary, he will be positioned as the de facto front-runner in the general election in November. Other candidates include Mayor Eric Adams, who has record low approval ratings and is running as an independent. Curtis Sliwa, the founder of the Guardian Angels, is the Republican candidate. Mr. Cuomo may run on an independent ballot line; Jim Walden is also running as an independent.
Voters seemed deeply divided as they visited the polls in sweltering weather on Tuesday. Many younger New Yorkers expressed enthusiasm for Mr. Mamdani.
Yadelis Avila, 22, a daughter of Dominican immigrants in Washington Heights, in Manhattan, said she ranked Mr. Mamdani first and was worried about housing costs.
“I just feel like he’s someone that I could identify with,” she said, adding, “His parents are immigrants, so it’s just like I see myself in him, and I trust him.”
Hakeem Shaheed, 49, a health care worker who voted in Harlem, said he liked Mr. Mamdani’s proposal to freeze rents on nearly one million rent-stabilized units.
“The rent is really important to me because everything else means nothing if you can’t live here,” he said.
At a Democratic Socialists of America watch party in Brooklyn, the primary results thrilled Mamdani supporters.Credit…Victor J. Blue for The New York Times
Other voters praised Mr. Cuomo’s experience. Elise Fernandez, 45, who lives in Jamaica, Queens, said she wants to the next mayor to address homelessness and traffic woes.
“No one is perfect, but he managed a whole state, so I can see he has the experience to manage and to do good for New York City,” she said.
The primary is the second time New York City has used ranked-choice voting in a mayoral primary. The campaigns scrambled to educate voters about the system, which almost led to an upset against Mr. Adams in 2021. He won the Democratic primary by less than 8,000 votes over Kathryn Garcia, a city sanitation commissioner who was endorsed by another candidate, Andrew Yang.
Mr. Adams, the city’s second Black mayor, has had a turbulent first term. He was indicted last year on federal corruption charges that were later dropped by the Trump administration after he struck an alliance with President Trump. Many of the mayor’s advisers were investigated and resigned; others resigned in protest over his cooperation with Mr. Trump.
Mr. Adams said on Tuesday night that he was ready to fight Mr. Mamdani in November, arguing that Mr. Mamdani “has no record.”
“It’s time to unite,” he said. “We have a city to save.”
Reporting was contributed by Dana Rubinstein, Samantha Latson, Sean Piccoli, Molly Longman, Nate Schweber and Amogh Vaz.
