North Carolina Republican Party officials are signaling that they might support a new election in the House race between Republican Mark Harris and Democrat Dan McCready, amid reports of possible illegal ballot harvesting and fraud by a GOP-linked operative.

McCready uploaded a video to Twitter on Thursday afternoon retracting his concession last month and condemning what he called "shameful criminal activity bankrolled by my opponent."

Unofficial totals have Harris leading McCready by 905 votes, with some counties reporting unusually high numbers of unreturned absentee ballots and a surprisingly strong showing by Harris in mail-in balloting that far exceeded his support during in-person voting.

"I didn’t serve 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. "Today I withdraw my concession and call on Mark Harris to end his silence and tell us exactly what he knew, and when."

In the video, McCready said Harris has remained "completely silent."

Meanwhile, House Democratic leader Nancy Pelosi said the House "retains the right to decide who is seated" and could take the "extraordinary step" of calling for a new election if the winner in the state's 9th Congressional District isn't clear.

And incoming Democratic Majority Leader Rep. Steny Hoyer, D-Md., said Tuesday that a "very substantial question" about fraud hangs over the race for a seat Republicans have held since 1963. He also suggested Democrats could refuse to seat Harris.

The state elections board refused to certify the results in the race last week because of allegations of "irregularities and concerted fraudulent activities" involving mail-in ballots in the district.

The board is meeting later this month to hear evidence, but it's unclear whether the race will be settled then.

The Republican Party of North Carolina (NCGOP) said the board's public findings will be critical.

"To sum it up, we think the Board of Elections should hold a public hearing and fully lay out the facts," NCGOP Executive Director Dallas Woodhouse said in a statement to Fox News. "If they can show with certainty that the outcome could NOT have been changed, they need to certify Dr. Harris and continue to support all state and federal criminal investigations. If they can show a substantial likelihood it could have changed the race, then we fully would support a new election."

BALLOT HARVESTING IS LEGAL IN CALIFORNIA, BUT NOT NORTH CAROLINA -- IS IT RIFE FOR ABUSE?

Woodhouse continued: "If they hold a public hearing and simply can’t determine one way or the other then, we would not oppose a short delay on the question of certification until they have more answers."

Entertaining the idea of a new election represents a significant change from last Thursday, when state GOP Chairman Robin Hayes issued a statement saying: "Democrats are throwing everything, including the kitchen sink, at the wall to try and steal an election."

"Today I withdraw my concession and call on Mark Harris to end his silence and tell us exactly what he knew." — Democrat Dan McCready

On Sunday, Hayes said there weren't enough questioned ballots to change the race's outcome, and the next day he accused a Democratic member of the state board of "score-settling."

On Wednesday, the editorial board of The Charlotte Observer wrote that the election had been "tainted" and that a new election is almost certainly required. "Individuals have interfered with the voting process by gaining access to others’ absentee ballots," the paper wrote.

The brouhaha highlights the wildly varying state laws governing ballot harvesting, which refers to the practice of someone other than a voter dropping off that voter's ballot at a polling station.

Two years ago, California Gov. Jerry Brown signed into law AB1921, which now permits anyone -- including political operatives -- to collect and return ballots in that state. Previously, only the voter or close family members could perform that service.

Republicans have since openly suggested that the practice led to major irregularities in voting in California, where the GOP lost seats in several strongholds as votes continued to be counted well after Election Day.

But in North Carolina, state law still prohibits anyone other than a voter or a close family member from mailing in or dropping off that voter's ballot.

The elections board has subpoenaed documents from the Harris campaign, and is concentrating on activities linked to McCrae Dowless, a longtime political operative from Bladen County. Dowless worked as a contractor for Harris' chief strategist in the campaign, Harris campaign lawyer John Branch confirmed Tuesday.

A North Carolina voter, Ginger Eason, told Charlotte, N.C. station WSOC-TV on Monday that Dowless had paid her between $75 and $100 to collect absentee ballots in the 9th District.

“I was helping McCrae pick up ballots," Eason said.

In affidavits offered by the state Democratic Party, voters described a woman coming to their homes to collect their absentee ballots, whether or not they had been completed properly.

"If they can show a substantial likelihood it could have changed the race, then we fully would support a new election." — NCGOP Executive Director Dallas Woodhouse

Bladen County was the only county in the district where Harris won a majority of the mail-in ballots, according to unofficial election data. Bladen and Robeson County — where officials also have requested information — had the district's highest percentages of unreturned mail-in absentee ballots.

Blanden also recorded absentee ballot requests from a whopping 7.5 percent of registered voters, more than double the rate of virtually all other counties in the state. Just over 60 percent of returned absentee ballots in Blanden went for Harris, even though registered Republicans comprised less than 20 percent of all voters who sent in ballots in the county on Election Day.

Local officials said Wednesday that more than 1,000 absentee ballots likely cast by Democratic voters in the 9th Congressional District may have been destroyed.

“You’re looking at several thousand, possibly 2,000 absentee ballot requests from this most recent election. About 40 percent of those, it appears, at this point may not have been returned,” Wake County District Attorney Lorrin Freeman told CNN.

Freeman confirmed Monday that her office has been investigating “potential voting irregularities” in Bladen County since early this year.

Allegations about similarly apparent mail-in absentee ballot irregularities also surfaced two years ago in Blanden County during a tight election for governor.

If the allegations are accurate, "this is the biggest absentee fraud in a generation or two in North Carolina," said Gerry Cohen, an election law expert and former longtime legislative staff attorney. "North Carolina has a long history of this kind of thing, particularly in rural areas."

Dowless, who served prison time in 1995 for felony fraud and was convicted of felony perjury in 1992, has worked on get-out-the-vote efforts for various local and legislative candidates through the years.

Dowless put his name on an elections protest, backed at the time by the campaign of then-GOP Gov. Pat McCrory, that alleged a "massive scheme" by a local political group to run an "absentee ballot mill" to improperly submit votes for a write-in candidate for a position Dowless was seeking.

But the board peppered Dowless with questions about his own absentee ballot activities. Dowless acknowledged he hired people in 2016 to urge voters to turn in absentee ballot request forms, which is legal. In sworn testimony, Dowless said he never handled or filled out the actual ballots. The board dismissed Dowless' protest but sent all of its evidence to local and federal prosecutors.

Republican leaders had previously said Harris, a Southern Baptist minister, should be certified the winner, saying no evidence has been made public that shows he didn't get the most lawful votes.

"The campaign was not aware of any illegal conduct in connection with the 9th District race," Branch said in a statement.

Fox News' David Lewkowict, Louis Casiano and The Associated Press contributed to this report.