Mamdani’s rise reshapes New York Democrats, allies win congressional primaries

Zohran Mamdani turned his 2025 mayoral upset into a stronger claim on New York Democratic power, as all three candidates he backed won congressional primaries on June 23, 2026. The wins cut into the influence of House Democratic leadership and showed that a disciplined left coalition could still beat better-funded party favorites in New York City.

Mamdani first forced that reckoning a year earlier, when he defeated ten other candidates in the New York City Democratic mayoral primary on June 24, 2025, taking 56% in the third round of ranked-choice voting to Andrew Cuomo’s 44%. The general election had been scheduled for November 4, 2025, but Eric Adams, who had initially sought re-election as an independent, later withdrew from the race on September 28, 2025. By then, Mamdani had already become the kind of citywide figure who could move votes beyond one office.

He used that capital to back a new slate, and the results were blunt. Brad Lander, the former city comptroller, beat Dan Goldman. Other Mamdani-backed candidates defeated establishment-backed Democrats in races tied to Adriano Espaillat, while Claire Valdez beat the handpicked successor to retiring Rep. Nydia Velazquez. One of the most visible of the challengers was Darializa Avila Chevalier, a 32-year-old doctoral student at the City University of New York and a community organizer who helped organize pro-Palestinian campus protests.

The campaigns leaned on a tight message: worker rights, affordability, immigration and criticism of Israel’s war in Gaza. At a rally with Bernie Sanders on June 18, Mamdani said, “The Democratic Party must change.” Sanders told the crowd that establishment Democratic politics were “no longer good enough.” Mamdani added, “The party of the past will not be what leads us into the future. We need a Democratic Party with backbone.”

That message held even as opponents complained about outside money and dismissed the rallies as politics as usual. Hakeem Jeffries campaigned against the Mamdani-backed candidates and still came up short, a result that signaled Mamdani’s rise was no longer just a mayoral story. It had become a warning to Democratic operatives well beyond New York that the party machine can still be beaten when the organizing is local, the message is fixed, and the coalition turns out.