Chris Rabb, a progressive state representative and self-styled “rabble-rouser,” clinched the Democratic nomination Tuesday for the nation’s bluest House district.

Rabb is all but guaranteed to succeed retiring Rep. Dwight Evans in Pennsylvania’s 3rd District. It’s a major win for the party’s left flank and a significant blow to the city’s storied political machine, which split between two other candidates in the race.

The progressive five-term state lawmaker toppled state Sen. Sharif Street, a former state Democratic Party chair and scion of a prominent North Philadelphia political family who had the backing of much of the city’s establishment. He also defeated Evans’ preferred successor, Ala Stanford, a pediatric surgeon who was running her first political campaign.

The race became a microcosm of the ideological and stylistic fights roiling the party nationally and a proxy battle between its progressive and center-left wings.

In a field where each candidate claimed progressive bona fides, Rabb tacked furthest to the left. He racked up endorsements from members of the “Squad,” won the backing of the local chapters of the Working Families Party and Democratic Socialists of America and held rallies with Rep. Alexandria Ocasio-Cortez (D-N.Y.) and polarizing left-wing political streamer Hasan Piker.

He pushed his rivals to join him in calling Israel’s war in Gaza a “genocide” and attempted to tie his competitors to the American Israel Public Affairs Committee, which has become a lightning rod in Democratic primaries. AIPAC said it was not involved in the race.

His victory is as much an exclamation point for progressives as it is a remarkable rebuke of Philadelphia’s Democratic machine.

In an interview ahead of Election Day, Rabb said his win would signal “that the era of establishment politics is coming to an end.” Nationally, he said it would show that “folks who are framed as radical or far left by mainstream media and establishment politics … are very much in the moral center.”