Abdul el Sayed achieved what progressives are hailing as the Democratic Party’s “biggest upset” in modern politics with his Michigan Senate primary win against establishment-backed Rep. Haley Stevens (D-MI).

But the progressive insurgent, supported by socialists like Sen. Bernie Sanders (I-VT) and Rep. Alexandria Ocasio-Cortez (D-NY), now faces his biggest test of all following a bruising primary to win over centrists, independents, and nonvoters in a general election against Republican Mike Rogers.