New York Gov. Andrew Cuomo holds a commanding 35-point lead over his Republican challenger in this fall's general election, according to a new Wall Street Journal/NBC 4 New York/Marist poll—the first since the conclusion of the legislative session and the start of campaign season.

Mr. Cuomo, a Democrat, leads Westchester County Executive Rob Astorino 59% to 24% among registered voters statewide, and third-party candidate Howie Hawkins receives 6%, the poll found; Mr. Astorino has virtually the same total as he did in March....