RALEIGH, N.C. (AP) — North Carolina officials set a Sept. 10 date for a new election for the nation’s last unresolved congressional race after the November results were thrown out over concerns of ballot tampering. Parties will hold their primaries on May 14.

The state elections board determined a new election was needed in the 9th congressional district after hearing days of evidence that tended to show a political operative working for Republican candidate Mark Harris hired people to collect mail-in ballots, which would have made votes vulnerable to being changed or discarded. North Carolina law prohibits anyone other than a voter or immediate family member from handling a mail-in ballot.

If no candidate gets at least 30 percent of the votes in the May primary, a second primary will be held on Sept. 10 and the general election will take place on Nov. 5, the board decided Monday.

The extended timetable was required to allow enough time for absentee ballots to be requested and mailed back, including by military members and their families who may be stationed abroad but who live in the 9th district near the Army’s Fort Bragg, elections board chairman Robert Cordle said.

Harris had narrowly led Democrat Dan McCready, but the elections board refused to certify November’s results pending an investigation. McCready is running again in the new election. Harris isn’t, citing health problems.