Rep. Michelle Steel, a two-term incumbent in California’s 45th congressional district, 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.

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.

In a major victory for Democrats, first-time candidate Derek Tran defeated Republican Rep. Michelle Steel in a hotly contested Orange County congressional race that became one of the most expensive in the country.