Mr. Lasher, the chosen successor of Representative Jerrold Nadler, beat a field of Democratic candidates that included a fellow state assemblyman in a race for a coveted open seat.
Congressional primaries in Manhattan, Brooklyn and beyond could test the strength of Mayor Zohran Mamdani’s socialist movement and reverberate across the country.
The congressional primaries in New York on Tuesday will answer key questions about the potency of super PACs and the extent of Zohran Mamdani’s influence.
Ms. Valdez, a first-term state lawmaker, defeated the Brooklyn borough president, Antonio Reynoso, to win an open House seat in a district divided along demographic fault lines.
Democratic leaders found that their traditional tools, from rallies to phone banks to big-name campaign events, were no match for the left’s ground game and messaging.
New York Republican leaders began a targeted ad campaign, trying to persuade Jewish voters to change parties by accusing Mayor Zohran Mamdani of fostering antisemitism.
Ronald S. Lauder, a major funder of conservative political causes, has not given a single dollar this year to Republicans in his home state, and his super PAC has gone idle.
