The Arizona Democrat is challenging the disqualification of 133 ballots.
It will be DCCC Executive Director Kelly Ward's third cycle with the group.
Democratic Reps. Jim Costa and Ami Bera appear to have survived close calls.
"My success in this position is because of their dedication to this office," said Rep. John Barrow (D-Ga.).
Rep. Steven Horsford (D-Nev.), who lost reelection in an upset, is eying a 2016 rematch.
The surprise pick of Rep. Ben Ray Lujan (D-N.M.) makes him the first Hispanic DCCC chairman.
Former state Rep. Edward Casso (D-Colo.) is exploring a run against Rep. Mike Coffman (R).
Rep. Ben Ray Lujan (D-N.M.) will be the next chairman of the DCCC for the 2016 cycle.
A CNN report says the NRCC and outside groups used anonymous accounts to share information.
Rep. Jim Costa (D-Calif.) is ahead of farmer Johnny Tacherra (R) by 700 votes.