The letters were sent partly in response to October's elections board hearing involving former Gov. Mike Easley's campaign. The former two-term Democrat has already been penalized $100,000 by the committee for failing to disclose dozens of campaign flights piloted by a close political ally.
During that hearing, a private investigator for the Easley campaign testified he couldn't find evidence in campaign reports of three Republican candidates that they had reported airplane flights -- as either in-kind contributions or expenses -- even though media reports and flight records pointed to them taking trips.
The request doesn't appear to be focused on punishing candidates for errors. The board also has been auditing the reports of dozens of campaign committees and asking them to file amendments to fix mistakes.
"It is my understanding that the intent of this inquiry is to ensure that all reports are accurate," deputy elections director Kim Strach wrote Tuesday in an e-mail. "However, if information suggested that there was a willful attempt to evade disclosure, then I am sure the board would address those actions."
Bill Graham, an unsuccessful Republican candidate in 2008 identified by the private investigator, said Tuesday board staff told his campaign treasurer to disregard the letter because it had already complied.
Board officials had reviewed its method of paying for flight-related expenses from a plane through Graham's Salisbury law firm using personal monetary loans Graham made to the campaign, treasurer Dave McCoy said.
"We did make sure that our methods of reporting was correct with the state board," Graham said.
Strach said her office has "no information to suggest that (Graham) has not accurately disclosed or properly reimbursed for flights."
Another 2008 GOP candidate, Fred Smith of Clayton, traveled on his personal jet during the campaign. The private investigator also identified 2004 GOP nominee Patrick Ballantine.
Since August, Perdue's campaign has identified 31 previously undisclosed flights since 2000 valued at more than $25,000, with the last batch identified to the state board two weeks ago. Campaign officials performed a self-audit last year after they noticed some inconsistencies in their data during the transition to a new computer reporting system in 2007.
State Republican leaders criticized Perdue's disclosures, saying they aren't much different from Easley's flights. Federal prosecutors last year sought information on Easley's airplane travel, while a district attorney is examining whether Easley or someone else broke state laws related to evidence in the October board hearing.
Perdue's campaign said it had contacted the board officials two years ago about the software issue and told them it would perform an external review, which uncovered the undisclosed flights.