Mark Harris, Republican candidate in North Carolina's 9th Congressional District, makes a statement before the state board of elections calling for a new election Thursday. (Travis Long/AP)

AT A meeting this month of North Carolina’s Republican executive committee, Mark Harris, the party’s candidate in last fall’s disputed election for 9th Congressional District, called allegations of absentee-ballot tampering “unsubstantiated slandering.” He said “the Democrats and liberal media have spared no expense disparaging my good name” and blamed “a liberal activist” on the state election board for preventing his certification as winner. But confronted last week with damning testimony, including from his own son, Mr. Harris had no choice but to change his tune and concede the election was so tainted that a new election was in order.

The reversal, four days into a state election board hearing, may well have spared Mr. Harris from what promised to be withering cross-examination. But it doesn’t free him from the need to answer questions about whether he was personally involved in wrongdoing and why he seemingly tried to mislead the public. Voters were cheated of a fair election, denying the 9th District representation in Congress until a new vote is held. That should not go unpunished.

At the center of the controversy is the activity of a political operative hired by Mr. Harris who is alleged to have orchestrated a scheme in which workers illegally collected, filled out and forged mail-in ballots in two rural counties. Mr. Harris, in testimony Thursday morning, denied knowing of any wrongdoing in the voter-turnout work done by Leslie McCrae Dowless Jr. Then his attorney abruptly stopped the questioning. When he returned to the stand after a two-hour break, Mr. Harris read a statement that acknowledged some of his testimony was incorrect and blamed medical issues.

It seems pretty clear that until Mr. Harris had to reckon with his son’s testimony about warning him to stay clear of the dubious Mr. Dowless, he was willing to ride his shaky 905-vote lead over Democratic candidate Dan McCready to a seat in Congress. Going along on that ride was a Republican Party establishment willing to look the other way at voter fraud as long as it worked to the party’s political advantage. It’s fortunate that election officials — with the help of on-the-ground reporting from local media — uncovered a scheme that was a blatant offense to democracy.