NYC Mayor Mamdani's Influence Tested in Key Congressional Primaries

On Tuesday night, New York City Mayor Zohran Mamdani faces his first major electoral test since his election in November 2025. While Mamdani isn't on the ballot, his power to swing voters is.

Mamdani has endorsed three candidates in competitive congressional primaries in the city: former New York City Comptroller Brad Lander in New York's 10th Congressional District, state Assemblymember Claire Valdez in the 7th District and first-time candidate Darializa Avila Chevalier in the 13th District.

Traders on prediction market platform Kalshi think the mayor will go two for three.

Speculators place 54% odds that Valdez and Lander will be victorious, while Chevalier will lose. They also give a 28% chance that all three candidates win and a 20% chance that only Lander wins.

Those odds are based on combo contracts, where all three events of each individual candidate either winning or losing need to happen for the trades to resolve to "yes." Outcomes on the combo contracts are verified from the New York State Board of Elections.

Odds and gambling platforms do not use methodologies used by traditional political polling, and therefore are not substitutes for political polls.

Lander, an ally of Mamdani, is challenging Democratic incumbent Rep. Dan Goldman. Goldman has been under fire from left-leaning critics for his support of Israel in the district that includes downtown Manhattan and Park Slope in Brooklyn.

On a contract that asks if a candidate will win the democratic nomination in New York's 10th District, Kalshi traders give Lander a near-certain chance of winning the Democratic nomination. Outcomes on individual nominee contracts are verified from the Democratic Party.

Valdez is seeking to replace retiring Rep. Nydia Velázquez in the 7th — which includes Williamsburg in Brooklyn and Long Island City in Queens — though Velázquez endorsed Brooklyn Borough President Antonio Reynoso. Reynoso has the backing of the progressive Working Families Party, while Valdez has the backing of the Democratic Socialists of America.

Traders on Kalshi think Valdez is favored; they are giving her a nearly 80% chance of winning the Democratic nomination.

Lastly, Chevalier — also backed by the Democratic Socialists of America — is seeking to oust incumbent Rep. Adriano Espaillat, chair of the Congressional Hispanic Caucus. The 13th District covers Harlem and Washington Heights in Manhattan, as well as parts of the Bronx. Traders on Kalshi give Espaillat two-in-three odds of fending off the challenge from Chevalier.

Meanwhile, there's another contentious primary in New York's 12th District, which covers midtown, the Upper East Side and the Upper West Side in Manhattan. Mamdani didn't endorse a candidate in that race.

Rivaling artificial intelligence super PACs are seeking to affect the candidacy of Alex Bores, a New York state Assemblyman, who has been a fervent supporter of AI regulations. OpenAI-backed Leading the Future has spent $8 million opposing Bores, while Anthropic-backed Public First Action has spent $11 million supporting him.

However, Kalshi traders think that fellow state Assemblymember Micah Lasher is favored in the12th, giving him a 74% chance of winning the Democratic nomination.

Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a minority investment.