U.S. Army Veteran Derek Tran has won California 45th Congressional District, unseating Rep. Michelle Streel in one of the state's most closely-watched races.

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.

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.

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.

Tran, a Democrat and Orange-based attorney, increased his advantage to 581 votes, adding another 36 votes to his lead from Saturday’s tally. Monday’s total only included an update from Orange County’s registrar of voters; Los Angeles County’s election officials will resume providing vote updates on Tuesday.

Democrat Derek Tran has declared victory over Republican incumbent Michelle Steel in California’s 45th Congressional District as his lead grows to nearly 600 votes. What he’s saying: If elected, Tran,

New vote tallies from Orange and L.A. counties late Tuesday afternoon showed Tran expanding his lead to 613 votes over incumbent Steel.

Derek Tran maintained his lead over Rep. Michelle Steel in the highly competitive race for California’s 45th congressional district on Monday, still one of the closest House contests in the nation. Tran,