With a series of social media clips, Mr. Ghosh has managed to replicate Mr. Mamdani’s campaign vibe. In the videos, labeled with yellow and orange titles that match the campaign’s font, Mr. Ghosh proposes solutions for problems that make life difficult for ordinary New Yorkers, all delivered with a closed-mouth grin and nice-guy earnestness, reminiscent of the style that has helped catapult the real Zohran Mamdani to his wide lead going into November’s election.