Zohran Mamdani, New York City's mayor-elect, had majority support from voters under the age of 45, while over half of voters 65 and older supported Andrew Cuomo, according to ABC News exit polls.

Relative newcomers to New York City were some of the most likely voters in the state to vote for Mamdani, according to exit polls, with about 8 in 10 of those who have lived in New York City less than 10 years supporting Mamdani. He also earned over half of the support of New Yorker City voters who lived for over 10 years but were not born in New York. Voters who were born in New York City voted for Cuomo over Mamdani.

Nearly 2 in 10 voters said it was the first time they voted in a New York City mayoral election -- and by a more than 2-to-1 margin, they supported Mamdani over Cuomo, according to exit polls.

-ABC News' Emily Guskin

New York City mayor-elect Zohran Mamdani addressed President Donald Trump directly during this victory speech.

"Donald Trump, since I know you're watching. Four words for you: Turn the volume up," Mamdani said to deafening cheers.

Mamdani has been a high-profile target of Trump -- who has branded the Democratic Socialist as a "communist" and vowed political retribution.

Mamdani, who was born in Uganda, vowed to protect immigrants, saying, "New York will remain a city of immigrants, a city built by immigrants, and as of tonight, led by immigrants."

"So hear me, President Trump, when I say this: To get to any of us, you will have to get through all of us," he said to applause.

During Mamdani's speech, Trump -- who threatened to slash federal funding to New York City if Mamdani won -- posted on social media, "…AND SO IT BEGINS!"

After thanking his volunteers who "built this campaign into an unstoppable force," New York City mayor-elect Zohran Mamdani urged the city to "breathe this moment in."

"We have held our breath for longer than we know. We have held it in anticipation of defeat. Held it because the air has been knocked out of our lungs too many times to count. Held it because we cannot afford to exhale," he said. "Thanks to all of those who sacrificed so much, we are breathing in the air of a city that has been reborn."

He spoke of his campaign promises to freeze rent for more than 2 million rent-stabilized tenants, make buses free and deliver universal child care, calling it "the most ambitious agenda to tackle the cost-of-living crisis" in the city.

"Years from now, may our only regret be that this day took so long to come," he said. "This new age will be one of relentless improvement."

New York City mayor-elect Zohran Mamdani said New Yorkers have "toppled a political dynasty" during his victory speech following former New York Gov. Andrew Cuomo's concession.

"I wish Andrew Cuomo only the best in private life," Mamdani said to cheers, adding that tonight will be the "final time I utter his name as we turn the page on a politics that abandons the many and answers only to a few."

Mamdani began his victory speech with a quote from socialist Eugene V. Debs, saying, "The sun may have set over our city this evening, but as Eugene Debs once said, 'I can see the dawn of a better day for humanity.'"