Mamdani, 34, pulled off a historic win in New York’s mayoral race with a slew of promises aimed at making life more affordable for residents. The democratic socialist received more than 50% of votes, while former Governor Andrew Cuomo — who ran as an independent — got just over 40%. Republican Curtis Sliwa managed about 7%.

For Mamdani to keep his campaign promises, he’ll require more money from the federal government — which provided over $7 billion in revenue for the city’s budget this year. But Trump has already derided him as a “communist lunatic” and made clear that he’ll squeeze access to funds.

The mayor-elect was defiant in his victory speech. “If anyone can show a nation betrayed by Donald Trump how to defeat him, it is the city that gave rise to him,” Mamdani told supporters. “And if there is any way to terrify a despot, it is by dismantling the very conditions that allowed him to accumulate power.”

Republicans are already positioning Mamdani as their foil, labeling him and his proposals as representative of the Democratic Party, as they prepare for mid-term congressional elections next year.

House Speaker Mike Johnson, posting on X after the New York City election, said the consequences of the Mamdani victory “will be felt across our entire country” as it “cements the Democrat Party’s transformation to a radical, big-government socialist party.”

Johnson was making the comments even as moderate Democrats won elsewhere on Tuesday night. Abigail Spanberger, a former CIA officer, easily took the Virginia governor’s race. Mikie Sherrill, a Navy veteran and ex-prosecutor, triumphed in New Jersey.

California Governor Gavin Newsom also won a significant victory when his state’s voters approved Proposition 50, allowing a redrawing of congressional maps to favor Democrats before the 2026 midterms. that could potentially thwart Trump’s plan to keep control of the house.

Trump-Proofing

Trump has already shown he’s prepared to use federal money as a lever against Democrats.

One day into the government shutdown, the White House halted $18 billion in New York infrastructure funding citing concerns over diversity and inclusion practices. The move threatens a key source of funding for critical improvements to the region’s ageing transit systems, including the extension of the Second Avenue Subway and the Hudson River tunnel project.

Apart from getting into potential fights with the Trump administration over funding for health care and food programs, Mamdani is also primed for a clash over the president’s deportation campaign.

Mamdani has pledged to strengthen New York’s sanctuary city status, which limits the local government’s cooperation with federal agencies over immigration enforcement. And in a section titled “Trump-Proofing NYC” on his campaign website, his platform calls for investing $165 million in funding for immigration legal defense services.

Democratic Tensions

But it’s not just Republican antagonists that Mamdani will have to contend with. The Democratic establishment is still skeptical about the Queens assemblyman, who has limited political work experience beyond his four years in the New York state legislature. The rapid rise of Mamdani — whose career included a stint as a rapper before his time in Albany — has caught the party’s old guard by surprise.

Democratic Governor Kathy Hochul waited for months to endorse him in the mayoral race, and has said she won’t approve tax hikes that the new mayor will need to fund his agenda. Senator Chuck Schumer, doyen of the party’s establishment wing and one of the country’s most-prominent Jewish politicians, never publicly backed Mamdani.

In October 2023, Mamdani was arrested outside Schumer’s Brooklyn home, protesting Israel’s actions in Gaza just days after Hamas attacked the Jewish state.

Wall Street billionaires and business leaders including Bill Ackman and Dan Loeb had also framed Mamdani’s policy proposals as a threat to New York’s financial health. Former Mayor Michael R. Bloomberg, the founder and majority owner of Bloomberg News parent Bloomberg LP, endorsed Cuomo in the primary and general election and has contributed to PACs supporting his candidacy.

“New York is on the verge of making a monumental mistake,” Home Depot Inc. co-founder Ken Langone said before the election, referring to the prospect of a Mamdani win. He compared the candidate’s policies to those that led to economic turmoil in Venezuela, Cuba and Argentina, adding that “capitalism works.”

But some on Wall Street are now adapting to the new reality. Ackman congratulated Mamdani after the election, telling the mayor-elect to “let me know what I can do.”

That Mamdani was able to win decisively shows the power of his appeal, and how much his charisma, social media savvy and messaging on affordability resonated with voters.

When he’s sworn in as New York City’s 111th mayor on Jan. 1, 2026, he will be the youngest person to hold the office in a century. He will also be its first Muslim leader and the first person of South Asian descent to hold the office in the city’s 400-year history. Mamdani only became a naturalized US citizen in 2018.

Lauren Klein, a Mamdani voter who works in art conservation and lives in Long Island City, said now that Mamdani is elected, she wants “more affordable housing, and an effective leader.” Another supporter, Jonathan Neer, said that he trusts Mamdani “to make a conscious effort.”

“Whether or not he will be a good mayor, I don’t know. But I trust him to try,” Neer said before stepping inside a Fort Greene bar in Brooklyn to watch Mamdani’s victory speech after Tuesday’s election.

Mamdani’s Promises

Mamdani has vowed to immediately start working to implement his campaign promises. Freeze rents in rent-stabilized apartments; provide free bus services; create a universal, free childcare program for children ages 6 months to 5 years; open five city-owned grocery stores, one in each borough — to name just a few.

Evan Roth Smith, a Democratic pollster and political consultant at Slingshot Strategies, said Mamdani’s narrow majority could help him in his appeal for more funding to make those pledges a reality.

“When he goes to Albany, when he goes to the federal government, he can say ‘I do have the majority of New Yorkers behind me when I asked for this,’” Roth Smith said.

“He’s going to have a tougher argument because it wasn’t 60% or 55%, it was 50 points and a hair,” he said.

And Mamdani’s promised rent freeze faces multiple hurdles — including the possibility that outgoing Mayor Eric Adams will stack the Rent Guidelines Board with his own appointees who won’t go along with a freeze.

All that means Mamdani risks disappointing his base of progressive voters if he isn’t able to fulfill his pledges once the euphoria over his win fades.

“The campaign is over, all the great promises,” said Apollo Global Management Inc. President Jim Zelter. Now, “it’s about delivering,” he said.

“You don’t celebrate the day you buy a company, you celebrate the day you sell it. There needs to be a change in tone and he needs to bring the city together,” Zelter said.