Democratic Pittsburgh Mayor Ed Gainey lost Tuesday’s mayoral primary election to the comparatively moderate Democratic Allegheny County Controller Corey O’Connor,

Democrat Corey O’Connor is almost certain to win the general election over Republican Tony Moreno, who won the GOP primary.

Corey O’Connor first toyed with the idea of trying to unseat Pittsburgh Mayor Ed Gainey about a year ago. In his role as Allegheny County controller, he often talked to residents throughout the city — and what he heard was frustration.

Ed Gainey, who was elected to be Pittsburgh’s first Black mayor nearly four years ago, will face Corey O’Connor, the Allegheny County Controller and well-funded son of a beloved former mayor. The primary will probably decide the general election as well, since Pittsburgh has not elected a Republican mayor in nearly a century.

Four things to know about the Pittsburgh mayoral race and what it could mean for the rest of Pennsylvania and the Democratic Party.

On Monday, as voters dropped off their mail-in ballots, many were focused on a single race: the match-up between incumbent Pittsburgh Mayor Ed Gainey and challenger County Controller Corey O’Connor.