The Republican candidate in the Ninth District, Mark Harris, asked for the new vote after testimony that his campaign had financed an illegal voter-turnout effort.

The details: Mr. Harris had a 905-vote lead over his Democratic opponent, Dan McCready, but regulators were alarmed that Mr. Harris won 61 percent of absentee ballots in a county where Republicans accounted for just 19 percent of them.

What’s next: The Ninth District, which includes part of Charlotte, will go unrepresented in Congress for at least several months. It was unclear whether Mr. Harris would run in the new election, which has not been scheduled.

Go deeper: This week’s testimony illuminated the inner workings of a precise but amateurish operation that paid workers to collect absentee ballots.