Democratic congressional candidate Julie Bornstein has conceded to U.S. Rep. Mary Bono Mack (R-Palm Springs) in the 45th Congressional District.

Although there are upwards of 100,000 ballots left to be counted, Bornstein was trailing the eight-term incumbent by nearly 15 percent as of Thursday afternoon.

"While there are about 100,000 ballots left to be counted in our race, it appears now that Mary Bono Mack has won re-election in California's 45th Congressional District," Bornstein said in a statement to supporters. "I congratulate her."

Bornstein added that she hopes Bono Mack "will return to Washington to work in a truly bipartisan and constructive way with the Democratic majority and President Obama's administration."

Bornstein applauded her supporters, noting that "we closed the registration gap by more than half, mounted the first-ever comprehensive ground effort and made great gains at the ballot box."