A U.S. House election in North Carolina has been called into question as election officials launch an investigation into possible voter fraud that took place in parts of the state.

Members of North Carolina’s State Board of Elections and Ethics are investigating multiple reports from residents of the state’s 9th Congressional district of suspicious incidents involving absentee ballots.

Republican Mark Harris called by the AP as the winner of the district, though now election officials are refusing to certify his victory over Democrat Dan McCready due to the probe.

Harris  defeated McCready by a slim 905 votes.

Residents of Bladen and Robeson counties claim that individuals came to their doors prior to Election Day to collect their absentee ballots, many of which were incomplete or taken and placed in unsealed envelopes.

State laws prohibit anyone other than the individual casting the vote or their “near relative” from turning in absentee ballots.

State investigators are looking into the disparity between the number of absentee ballots requested by members of the community and the comparatively low number of ballots actually turned in.

Members of the State Election Board are all too familiar with these types of voter irregularities, according to Joshua Malcolm, the board’s vice president.

“I’m very familiar with the unfortunate activities that have happened in my part of the state,” he said on Tuesday, according to WFAE. “And I am not going to turn a blind eye to what took place to the best of my understanding, which has been ongoing for a number of years, and which has been repeatedly referred to the United States attorney and the district attorneys to clean up. Those things have not taken place.”

On Thursday, North Carolina Democrats sent a letter to the state board demanding a public hearing to review the evidence surrounding the case.

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McCready, who had previously conceded the race, voiced his support for the investigation and called for a hearing in a statement on Thursday.

State Republicans have threatened legal action against the election board if it does not certify the election results.

“There are simply not enough absentee ballots in question to change the result,” read a press release published by the North Carolina Republican Party on Thursday. “Mark Harris was elected to Congress. Mark Harris is going to Congress. Democrats don’t get a do-over based on unverified rumors that were not even put in an official election protest as required by law.”

Officials will meet Friday morning to decide whether they will certify the results.