June 17 (UPI) -- Sen. Bernie Sanders , I-Vt., has thrown support to a pair of progressive candidates running in Democratic primaries against more established candidates. Sanders is expected to officially endorse Zohran Mamdani in the party's mayoral primary in New York City on Tuesday. A Brooklyn native, Sanders joins Rep. Alexandria Ocasio-Cortez , D-N.Y. in support of Mamdani, a left-wing Democrat who must compete against former New York Gov. Andrew Cuomo in the primary. Current mayor Eric