State Assemblyman Zohran Mamdani‘s upset victory over former Gov. Andrew Cuomo during New York‘s Democratic mayoral primary on Tuesday puts establishment Democrats in a tough position.

A self-proclaimed socialist with less than five years of legislative experience under his belt, Mamdani, 33, built a grassroots campaign centered on affordability that promised to bring working-class voters a slew of progressive policies, including raising taxes on rich people, providing free public buses and child care, freezing rent in subsidized units, and creating government-run grocery stores.