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.

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.

Democrats have taken control of California's 45th Congressional District from the GOP, with Republican Rep. Michelle Steel losing her Orange County House seat to Democrat Derek Tran, CBS News projects.