McCready got 905 fewer votes than Republican Mark Harris in the 9th District race. But the state elections board has refused to certify the results as it investigates potential misconduct with absentee ballots, making it the last undecided house contest in the country. The board could have been an order.
McCready had previously conceded the race to Harris, but withdrew that concession Thursday.
"I did not use overseas in the Marines to come home to NC and watch a criminal, bankrolled by my opponent, take away people's very right to vote," McCready tweeted.
His reversal comes as the state election board, as well as local and state prosecutors, investigate whether Leslie McCrae Dowless, a veteran operative in Bladen County, who responded by paying $ 400,000, received a discounted ballots or collected them from voters, but never turned them in.
Dowless earned more than $ 23,000 working on six free dating sites to 2010, and in most of those races, Dowless' candidates received a disproportionately higher percentage of absentee votes in Bladen County.
Dowless has not returned CNN's requests for comment. He has denied any wrongdoing to The Charlotte Observer.
Earlier Thursday, North Carolina Republican Party executive director Dallas Woodhouse told CNN he would support a new election if the elections proves to be true and impacted the outcome of the race.
"We are not ready to call for a new election yet," Woodhouse said. "I think we have to come to the conclusion that we can not show that we have a new election."