NEW YORK − Zohran Mamdani, a 33-year-old Democratic Socialist state Assembly member, upset mainstream Democratic politics by defying expectations and taking a commanding lead in the June 24 New York City mayoral primary.

Just after midnight, he addressed supporters, saying he and former Gov. Andrew Cuomo, the moderate Democrat who was the frontrunner, need to bring the nation’s largest city together.

“Tonight, we made history,” Mamdani boasted to a celebrating crowd in Queens.

With 96% of the vote counted, Mamdani led Cuomo 44% to 36% in first place votes.

Less than two hours after polls closed on June 24, former Gov. Andrew Cuomo, 67, had said he already called Mamdani to congratulate him on his historic campaign.

“Tonight is his night,” Cuomo told supporters at his election night party. “He deserved it. He won.”

The subsequent instant runoff, in which other candidates’ supporters will be redistributed to Mamdani or Cuomo based on who they ranked lower on their ballot, is expected to only increase Mamdani’s lead. Third-place finisher New York City Comptroller Brad Lander had encouraged his voters to rank Mamdani second.

As Mamdani declared victory, Lander joined him on stage.

“Together, we have shown the politics of the future, one of partnership and of sincerity,” Mamdani said.

Cuomo had led the polls by double-digit margins for months. The final poll released the day before the election showed Mamdani winning only by picking up more of Lander’s supporters in the final round of the runoff.

The race served as a bellwether for the larger Democratic Party, as the coalition seeking to repel Cuomo framed the choice facing New Yorkers as one between an older, moderate political establishment and a youthful, progressive vision for the party that lost the White House in November.

Mamdani has drawn comparisons to fellow Democratic Socialists of America member Rep. Alexandria Ocasio-Cortez, who in 2018 unseated Joe Crowley, the Chair of the House Democratic Caucus, in a Bronx and Queens district that overlaps with Mamdani’s Assembly seat. She endorsed Mamdani, as did Sen. Bernie Sanders, the independent progressive icon from Vermont.

On the other side, heavyweight mainstream Democrats backed Cuomo. Nationally, they included former President Bill Clinton and Rep. Jim Clyburn, who revived former President Joe Biden’s 2020 campaign. And New York’s political establishment, such as Rep. Adriano Espaillat and Brooklyn Democratic Party chair Rodneyse Bichotte-Hermelyn, backed Cuomo too.

‘He gave us something to believe in’

Mamdani turned out younger voters on a platform centered on addressing affordability in America’s largest city. Cuomo sought to draw on decades of experience in government as a bulwark against Trump’s attacks on his hometown. Voters gave Mamdani a chance to change their notoriously expensive hometown.

“With a vision of a city every New Yorker could afford, we have won,” Mamdani said.

Mamdani said his city would be one “governed as a model for the Democratic Party,” which would prioritize the needs of the working class and fight Trump.

Rep. Nydia Velazquez, a left-leaning Democrat who represents a Brooklyn-based district, said Mamdani won with a simple message of affordability for all.

“He gave us something to believe in,” Velazquez said at his election night party. She said his campaign threatens billionaires in power.

“But here’s the thing: The city has changed,” Velazquez said. “Zohran knew it.”

If elected, Mamdani, who was born in Uganda and is of Indian ancestry, would become the first Muslim and Asian American mayor of New York City, and its youngest mayor in a century.

He would represent a stark ideological departure from incumbent Mayor Eric Adams, a conservative Democrat and former Republican who has become increasingly friendly with Trump ever since he was indicted for corruption by the Justice Department under former President Joe Biden. (The department dropped the charges after Trump took office, saying the case would impede Adams’ ability to cooperate with federal immigration enforcement.)

Cuomo led by wide margins throughout the primary, but polling narrowed in the days leading up to election. A Super PAC funded in part by former Mayor Mike Bloomberg and several major donors to President Donald Trump poured $24 million against Mamdani, trying to paint him as a radical and antisemitic.

Mamdani would now have an advantage as the Democratic candidate for mayor in an overwhelmingly Democratic city, in which many feel besieged by President Donald Trump’s aggressive crackdown on undocumented immigrants, his assault on Columbia University, and proposed cuts to social welfare programs.

However, the race ahead into November represents a more fractured moderate Democratic politics than previously seen.

But he still faces opponents in November including Republican challenger Curtis Sliwa, a conservative talk show host and longtime local activist. Adams is running for reelection as an independent, and Cuomo may do so as well.

Mamdani’s opponents will likely continue to attack him for his views on Israel, which have drawn criticism from some Jewish groups, and his relative inexperience as third-term lawmaker with a very modest record of legislative accomplishment.

Mamdani ran a social media savvy campaign that featured viral videos such as him speaking to working-class voters in the Bronx and Queens who voted for Trump on issues about the cost of living. Mamdani campaigned on promises to freeze the rent in rent-stabilized apartments − he took a winter plunge in the Atlantic Ocean to make the freeze literal in one video − make buses free and provide universal child care. Those proposals appealed to a city of mostly renters, many of whom are struggling to remain in Gotham.

But he also ran a campaign heavy on expansive canvassing and door-knocking across the five boroughs. On the first night of summer, Mamdani walked the entirety of the island of Manhattan, which stretches about 13 miles, to encourage people to get out amid early voting.

While Cuomo enjoyed vast familiarity and some loyalty, he was also a vulnerable frontrunner due to accusations of sexual harassment, hiding COVID-19 deaths, and bullying in the state Capitol as governor, which contributed to his 2021 resignation.

“We’re done with him,” Lander, a progressive candidate who campaigned alongside Mamdani, told his supporters. “Andrew Cuomo is in the past. He is not the present or the future of New York City.”

The city’s ranked choice voting system requires candidates to surpass 50% of first-round votes to win. The Cuomo campaign apparently saw it won’t get second- or third-round votes from the other candidates that could put him over the edge against Mamdani.

Still, votes will be tallied over the next week as the system eliminates the lowest vote-getting candidates, and redistributes their subsequent votes to the remaining candidates. Given the coalition, the votes are unlikely to favor Cuomo, or at least he thought.

After the tallies, the race continues to November.

Mamdani said his campaign renewed faith in democracy. Voters, he said, can feel helpless in the face of government confusion and weakness and desperately sacrifice their liberties over basic needs.

“We have given our city permission to believe again,” he said.