Washington (CNN) California Democrat Gil Cisneros has defeated Republican Young Kim in a closely watched House race, adding yet another blue seat to the party's new House majority.

Cisneros, a former Navy officer, will represent California's racially diverse 39th Congressional District, which was previously held by retiring Republican Rep. Ed Royce.

Kim, who was seen as a charismatic potential successor to Royce, her one-time boss, finally succumbed to her opponent on Sunday.

In a concession published to Facebook, Kim said she believes that the "competitive nature of this election shows that my message and service to this community resonated."

The Democratic win in the district adds to several other pickups for the party in the districts representing Orange County, a place that used to be reliably Republican. Democrats now control seven seats representing the county, four of which are pickups from Republicans.