Democrat Derek Tran has defeated Republican incumbent Michelle Steel for a House seat representing California’s Orange County and Los Angeles, NBC News projects, after a contentious race that centered on the candidates’ Asian American identities and use of aggressive anti-China messaging.

Derek Tran maintained his lead over Rep. Michelle Steel in the highly competitive race for California’s 45th congressional district on Tuesday, still one of the closest House contests in the nation. Tran, a Democrat and Orange-based attorney, increased his advantage to 613 votes, adding another 32 votes to his lead from Monday’s tally.

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.