(Reuters) - North Carolina’s board of elections named political consultant Leslie McCrae Dowless as a person of interest on Friday amid a probe of possible absentee ballot fraud in a disputed U.S. congressional election.

The board has refused to certify Republican Mark Harris as the winner of the Nov. 6 election for a seat in the U.S. House of Representatives as it investigates possible fraud involving absentee ballots from two rural counties.

In a statement, the board said it has assigned four investigators to the probe and issued subpoenas to the Red Dome Group, a consulting firm that Dowless performed work for, along with the Harris campaign committee and the campaign for a local Bladen County sheriff candidate.

Residents in rural Bladen County have provided sworn affidavits that people came to their homes to collect absentee ballots they had not filled in. In North Carolina, it is illegal for a third party to turn in absentee ballots.

Two women have told WSOC-TV in North Carolina that Dowless paid them to collect absentee ballots and deliver them to him. Dowless worked for the Red Dome Group, the station reported. Neither Dowless nor Red Dome has responded to requests for comment.

Bladen and another rural community under review, Robeson County, saw high interest in absentee ballots this year with abnormally large numbers of ballots unreturned, according to an analysis by Michael Bitzer, a politics and history professor at Catawba College in North Carolina.

If fraud is uncovered, the board could order a new election. Harris edged out Democrat Dan McCready by 905 votes last month, but McCready on Thursday withdrew his concession.

In a video posted on Twitter on Friday, Harris said he was unaware of any wrongdoing and that his campaign was cooperating with the investigation.

“If this investigation finds proof of illegal activity on either side to such a level that it could have changed the outcome of the election, then I would wholeheartedly support a new election to ensure all voters have confidence in the results,” he said.

A week ago, Harris had urged the board to immediately certify him as the winner while it conducted the investigation, saying there were not enough ballots at question to change the outcome.

Federal finance reports show Harris’ campaign paid more than $525,000 to the Red Dome Group during the election cycle, and owed it a total of $53,442 for work performed between mid-October and late November, including $34,310 for reimbursements for “Bladen absentee” and “door to door” efforts.

The elections board has said it would hold a hearing into the allegations on or before Dec. 21. North Carolina Republican Party leaders also have said they would support a public hearing and possibly a new election.

Democrats in the U.S. House are calling for an investigation and could rule on the contest when they take control of the chamber next year.

The elections board said after concerns surfaced in late October and early November about possible criminal absentee ballot activities, it mailed letters to about 2,000 Bladen County voters who had requested absentee ballots, explaining their rights and providing a hotline phone number.

“The hotline received 10 calls in response to the mailing, and that evidence is being considered by investigators,” the board said in its statement.

The board said it also investigated issues with absentee ballots in Bladen County in 2016, and provided prosecutors with detailed reports documenting issues raised and additional information obtained through investigations.