Racine (D) told The Washington Post in an interview that after he and his campaign staff were notified of the excessive donations by a reporter, they reviewed their records and refunded the money. It is not yet clear whether the violations will result in fines.
"What's important to note is that at the end of the day, I take full responsibility for those mistakes," Racine said. "There's a normal process of review when a contribution is made, and that normal process of review should certainly catch, if you will, excessive contributions by the same donor. That failed in those instances."
Racine, who is up for reelection next year and is also widely considered to be a potential challenger to Mayor Muriel E. Bowser (D), said any future donations would get extra scrutiny from his campaign team to make sure they complied with D.C. limits.
"I don't know the specifics of how it happened or where the lapses were," he said. "I do know that there were lapses, and that's enough for us to have good reason to redouble our efforts, period."
Sean Rankin, a Racine campaign adviser who is now executive director of the Democratic Attorneys General Association, said the five donors whose contributions were above legal limits were the Home Depot Political Action Committee, AT&T, Chester Burrell, Jeff Guimond and Clifford Barnes.
Rankin said the mistake arose in part from a glitch in the software used by the District's campaign-finance office that did not record the donations as over the limit when the campaign first reported them. "It's still our responsibility to have caught it, but we missed it, and the software missed it," Rankin said.
The District's campaign-finance regulators have been criticized in the past for lax enforcement of regulations.
Williams said candidates' campaigns are responsible for ensuring donations fall within legal limits. But he acknowledged that small variations in how contributors' information is entered by campaign officials could affect whether the District's filing system throws up a red flag.
Such variations were present in at least four of the five excessive Racine contributions, Williams said. "Going forward, we have made a number of enhancements to our electronic filing system to catch contributions such as this and we continue to seek more enhancements to improve our capabilities to do so," Williams wrote in an email.
The five excess donations represent a tiny fraction of the roughly $680,000 Racine raised from more than 1,300 donors for his 2014 campaign.
Such irregularities are not unusual. Two months ago, Bowser's campaign was fined $13,000 for accepting $11,000 in excessive donations from various donors.
From the standpoint of public perception, however, the illegal donations could prove problematic for Racine, who has positioned himself as a leading voice for government ethics reform.
The attorney general is pushing legislation before the D.C. Council that would bar contributors to political campaigns from bidding on city contracts. The bill is aimed at curbing what is widely viewed as a "pay-to-play" culture in which donors obtain favorable treatment in their business dealings at City Hall.
"I sure hope not," Racine said, when asked whether his campaign's handling of the illegal contributions would affect that effort. "I hope that my mistake and the mistake of my campaign doesn't get in the way of what is a clear and strongly held view by District residents that campaign-finance legislation should pass."