Democrat Andy Kim defeated two-term Republican incumbent Rep. Tom MacArthur in New Jersey's 3rd District, leaving the GOP with just one House seat in the next Congress.

Kim, a former national security aide to Barack Obama, upset MacArthur in the hotly contested southern New Jersey district, widening the Democrats' edge in the House.

Kim declared victory last week, but MacArthur did not concede as mail-in and provisional ballots continued to be counted. The Associated Press called the race Wednesday.

Kim is the first Asian-American elected to the House from New Jersey. He has never run for or served in elected office before.

"This from the very beginning was always about the people," Kim told supporters at his office in Mount Laurel when he declared victory. "I will be part of that new generation of leaders what will step up and do what's best for the American people. That's what we need right now."

 A MacArthur spokesmen did not immediately respond Wednesday.

The district last elected a Democrat in 2008.