Rep. Michelle Steel, a two-term incumbent in California’s 45th congressional district, appears to have conceded to Derek Tran Wednesday afternoon after a long slog of a race that is one of the nation’s closest remaining contests yet to be called.

Derek Tran, a first-time Democratic candidate, has flipped a toss-up California House seat, narrowly defeating GOP Rep. Michelle Steel, who conceded on Wednesday after a protracted vote count. Tran had declared victory early this week, and currently leads by roughly 600 votes.

Democrat Derek Tran has defeated two-term Republican U.S. Rep. Michelle Steel in a Southern California House district that was specifically drawn to give Asian Americans a stronger voice on Capitol Hill.