New York CNN — Zohran Mamdani could barely walk a few feet at a recent Juneteenth festival in Queens without a crowd of selfie-demanding admirers trying to stop him. Mamdani is a 33-year-old state assemblyman and democratic socialist who’s surged in the campaign for New York City mayor with a mix of viral videos and proposals appealing to younger progressives. He’s capitalized on progressive frustration with Andrew Cuomo, the former New York governor mounting a political comeback with a mayoral run; in one of his videos, he explains New York City’s ranked-choice voting system in Hindi and Urdu and likens...