Incumbent Pittsburgh Mayor Ed Gainey lost his reelection bid in the Democratic primary on Tuesday to challenger Corey O’Connor.

O’Connor, the Allegheny County controller and son of former Mayor Bob O’Connor, denied Gainey a second term as mayor, leading 53% to 47% with nearly all precincts reporting. Because of the Steel City’s strong Democratic voter base, O’Connor is almost sure to win the general election over Republican Tony Moreno, who won the GOP primary Tuesday.