Brad Lander, backed by NYC Mayor Zohran Mamdani, won the Democratic primary for New York's 10th Congressional District on June 24, defeating two-term incumbent Rep. Dan Goldman with roughly 63% of the vote. Goldman had easily won reelection in 2024, but his popularity in the district dropped significantly, making him vulnerable to a primary challenge from the left. Mamdani's endorsement proved powerful — all three of his preferred congressional candidates won their primaries that day, signaling a shift in New York City Democratic politics toward democratic socialist candidates over establishment-backed incumbents.