Zohran Mamdani’s election as New York’s next mayor exposed a deepening rift between traditional Democratic Jewish voters and younger progressives — one that could reshape politics for years in the metropolitan area with the world’s largest Jewish population outside Israel.

Mamdani, a 34-year-old democratic socialist, handily defeated Andrew Cuomo, the Democratic former governor of New York who ran as an independent, while beating back accusations of antisemitism over his support of Palestinians in the conflict in Gaza.

A Muslim immigrant, Mamdani benefited from a wave of anger over Israel’s conduct in Gaza among some Democrats and Jewish Americans who had initially supported it but grew disillusioned. That shift manifested itself in spring protests at Columbia University last year that Mamdani supported and politically benefited from.

A Pew Research Center poll last year found that just half of Jewish Americans under 35 said the way Israel has carried out the war has been acceptable, while 68% of Jews ages 50 and older said it was acceptable.

In New York, about one-third of Jewish voters in Tuesday’s election supported Mamdani, exit polls showed, powering a victory that alarmed his Jewish opponents unaccustomed to backing the losing candidate.

“The morning after the election, many members of our community woke up with a sense of unease,” said Hindy Poupko, a senior vice president at the UJA-Federation of New York, a major Jewish nonprofit. “There’s a lot of uncertainty about how Mayor Mamdani might act once in City Hall.”

Mamdani was tested quickly. When in the hours after his election antisemitic graffiti was scrawled on a Brooklyn Jewish Day School, the mayor-elect condemned the act.