Zohran Mamdani has rallied young voters with a campaign focused on making New York City more affordable.

Zohran Mamdani was poised to deliver a stunning upset in the New York City’s mayoral primary that pitted youthful enthusiasm against Andrew Cuomo’s billionaire backers, union endorsements and old-guard Democratic support.

Mamdani raced to an early lead in the Democratic primary shortly after polls closed at 9 p.m. Tuesday, racking up more than 43% of the vote with roughly 90% of ballots counted. The official outcome of the race is still to be determined by a ranked-choice vote count.

Cuomo’s 36% of the vote read as a rebuke from the majority of Democratic voters, who didn’t turn out in the numbers he needed for a centrist campaign that promised more police and safer subways. Mamdani, a democratic socialist, campaigned on lowering the city’s costs of living.

“Tonight was not our night,” Cuomo told his supporters after conceding to Mamdani less than two hours after voting ended. “Tonight was Assemblyman Mamdani’s night, and he put together a great campaign and he touched young people and he inspired them.”

The 67-year-old, who got big-name endorsements from former President Bill Clinton, former Mayor Mike Bloomberg and some of the city’s biggest labor organizations, said he wasn’t ruling out a return to the race for the general election in November. Cuomo petitioned to get on the general election ballot under his own party in May.

“He’s going to look at the numbers, and he’s leaving the door open,” a Cuomo spokesman said late Tuesday.

Former New York Gov. Andrew Cuomo at an election night event in New York City on Tuesday.

Democratic strategist Trip Yang called the results “the biggest upset in modern New York City history.”

Even without an official result in the primary race, Mamdani’s supporters and Democratic competitors rushed to congratulate him. Rep. Alexandria Ocasio-Cortez, who lent her progressive voice to Mamdani’s campaign, shared her congratulations.

“Billionaires and lobbyists poured millions against you and our public finance system. And you won,” she wrote. Vermont Sen. Bernie Sanders also congratulated Mamdani, who he had endorsed in the race.

New York Gov. Kathy Hochul, who was once Cuomo’s lieutenant in Albany, praised Mamdani’s grassroots campaign. “I look forward to speaking with him in the days ahead about his ideas on how to ensure a safe, affordable, and livable New York City.”

Fellow primary candidate Brad Lander, third Tuesday with 11% of the vote, attended Mamdani’s postelection party later Tuesday. He, City Council Speaker Adrienne Adams and Brooklyn Sen. Zellnor Myrie had all been endorsed along with Mamdani on the Working Families Party progressive slate.

Supporters celebrating Tuesday during a watch party for Zohran Mamdani’s primary campaign.

All the Democrat candidates had urged voters to “Don’t Rank Cuomo,” part of a collective strategy to keep the former governor from winning in subsequent rounds of ballot–counting. But the ranked-choice gamesmanship turned out to be unnecessary after Mamdani defied expectations and shot out to a large lead. The Board of Elections had said there might not be a final result until at least July 1, the last day the board can receive mail-in ballots.

The 33-year-old set himself apart early on with a buzzy and viral social-media presence that gave him a solid following among younger and left-leaning voters who enthusiastically door-knocked for him in get-out-the-vote operations around the five boroughs.

“This is marking kind of a generational shift in the politics of the greater New York City area,” said John Gershman, a public-service professor who works on democracy- and election-related issues at New York University.

The Democratic primary winner will still face competition in the November general election. Along with the Republican candidate, Curtis Sliwa, and an independent, Jim Walden, the Democratic nominee will need to beat Mayor Eric Adams. The embattled incumbent opted to skip the primary and run in November under party lines he created: “Safe&Affordable” and “EndAntiSemitism.” He faces tough re-election odds after legal trouble last year.

Write to Alyssa Lukpat at [email protected], Victoria Albert at [email protected] and Jasmine Li at [email protected]