(CNN) - Republican Rep. Brian Bilbray conceded Friday to Democrat Scott Peters in California's 52nd congressional district, giving Democrats a net gain of five seats in the U.S. House of Representatives.
In a statement conceding the race, Bilbray congratulated his opponent and thanked his supporters.
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"This was an expensive and hard-fought campaign that drew national interest," Bilbray wrote. "I appreciate the spirited dialogue that often accompanies campaigns like this one. While Scott and I differ sharply on how to handle the issues facing our nation, now is the time to put those differences aside and find common ground to address our country's many challenges."
The latest results from the California secretary of state show Peters leading Bilbray by 2,660 votes.
Democrats maintain a slight lead in each of the three additional House races that remain too close to call.
A fourth unresolved House race in Louisiana will pit two Republican incumbents against each other in a December 8 run-off election.
The balance of power now stands at 234 Republicans, which includes the winner of the Louisiana race, and 198 Democrats. Before the election, Republicans held 242 seats and Democrats had 193.
The remaining races are Arizona's second district between Republican Martha McSally and Democratic incumbent Rep. Ron Barber; Florida's 18th district between Republican incumbent Rep. Allen West and Democrat Patrick Murphy; and North Carolina's seventh district between Republican David Rouzer and Democratic incumbent Rep. Mike McIntyre.
–CNN's Robert Yoon contributed to this report.