Mamdani, a 33-year-old state assemblyman representing northwest Queens, last month shocked the political establishment by trouncing the longtime front-runner, former Gov. Andrew Cuomo, whose name recognition, experience and support of billionaires and corporations, made him the favorite.

The United Federation of Teachers’ endorsement was the latest major labor union to coalesce around the Democratic mayoral nominee.

Former N.Y. Governor David Paterson questions the progressive candidate's readiness despite his primary win and polling lead.