Del. Robert G. Marshall, R-Prince William. (Bob Brown/AP)

Virginia Del. Robert G. Marshall (R-Prince William) has failed to respond to warnings about accepting campaign contributions over the legal limit more than a year after his failed bid for Congress, records show.

The lawmaker’s congressional campaign committee reported accepting $5,000 donations from three donors, according to the Federal Election Commission, over the $2,600 individual limit.

Marshall said he did not deal with the campaign treasury.

“My treasurer explained to me . . . a clerical error was made, an honest mistake that will be corrected as soon as possible by my treasurer,” Marshall said in an e-mail.

The almost $7,500 in excess contributions were less than a tenth of his total fundraising haul to succeed U.S. Rep. Frank R. Wolf.

The Federal Election Commission flagged the contributions in May and September 2014 in letters addressed to the treasurer, Mary Rose Lalli. The agency said the campaign faced enforcement action for taking more than a month to respond, but has not proposed penalties.

Candidates regularly receive excess contributions from donors who may not know the limits, but it is unusual to ignore warnings about them, said Paul S. Ryan of the Campaign Legal Center.

“It’s more common with low-dollar, less sophisticated and less serious politicians than with more professionalized campaigns, but it’s a bad idea for anyone to ignore the FEC,” said Ryan, whose organization advocates for more aggressive enforcement of federal campaign finance laws.

Neither Marshall nor Lalli answered questions about why the campaign didn’t respond to the FEC’s warnings.

Democrats have long targeted Marshall for his conservative stances on social issues, including co-authoring Virginia’s 2006 ban on same-sex marriage and suggesting women who had abortions are more likely to have children with disabilities. Marshall narrowly won reelection by three percentage points in 2013, the first close race since voters in his reliably conservative district elected him in 1992.

His Democratic challenger, Don Shaw, who first flagged the discrepancies in Marshall’s campaign finance, is now attacking Marshall as loose on ethics.

“It feels like he’s above the law,” said Shaw, a first-time candidate who works for a defense contractor. “In the wake of the many ethical issues we’ve had here in Virginia, our elected officials should know better.”

Shaw also criticized Marshall in January for accepting campaign donations during the legislative session, which is prohibited.

Marshall said the contribution page on his Web site was left up inadvertently and that he would return the one illegal $25 contribution he received. Authorities did not investigate or fine him over the error.

“If that’s the biggest complaint he has, I don’t know that that is earthshaking,” Marshall said in January.