RALEIGH, N.C. — A democratic presidential hopeful, John Edwards, who reiterated his commitment yesterday to never accept campaign donations from special interest groups, has returned thousands of dollars from lobbyists.

Edwards spokeswoman Colleen Murray said the campaign returned some money donated by a registered lobbyist last week, and money from two others was refunded yesterday.

“We take every precaution possible, but sometimes people slip through, and when we find lobbyist money, we refund it immediately,” Ms. Murray said.

Mr. Edwards has long eschewed campaign donations from lobbyists and political action committees, a stand dating to his first run at political office — a successful campaign in 1998 for a U.S. Senate seat in North Carolina. Asked about that policy yesterday during a campaign event in Georgetown, S.C., Mr. Edwards firmly declared himself clean of special interest donations.

“I’ve never taken political contributions from Washington lobbyists or PACs of any kind, and I’ll continue to do that,” Mr. Edwards said, drawing applause at a Steelworkers Union Hall.

But Robert Giroux, a lobbyist for the Service Employees International Union, contributed $1,500 to Mr. Edwards’s campaign in May, according to federal campaign finance and lobbying records. The records indicate the donation came in mid-May, a few weeks after Mr. Giroux registered as a lobbyist.

Randall Kelly, a veteran lobbyist who has represented the Affordable Housing Tax Credit Coalition, also gave Mr. Edwards a total of $1,500 over the past three months. Mr. Kelly has also contributed $500 to the campaign of Senator Dodd of Connecticut, who has decided to accept such money. Frank Lloyd, who is registered to lobby on behalf of Cablevision Systems Corp., donated $400 in June. Ms. Murray said Mr. Kelly’s donation was returned last week. The donations from Messrs. Giroux and Lloyd were refunded yesterday.

One of Mr. Edwards’s top Democratic rivals, Senator Obama of Illinois, has vowed repeatedly to refuse money from special interests during his run for the White House — a theme he echoed in a debate Monday night.

“We’ve got to get the national interests up front as opposed to the special interests,” said Mr. Obama, whose campaign in April refunded more than $50,000 in contributions after discovering the donors were lobbyists.

Mr. Edwards raised $23.1 million in the first half of 2006. That ranks him third among Democrats, but he lags far behind Senator Clinton of New York and Mr. Obama.