U.S. Rep. Pete Visclosky said he will repay thousands of dollars in campaign cash connected to a federally targeted Washington lobbying firm after taking a closer look at his ties to the company.

The Merrillville Democrat will return to the U.S. Treasury Department at least $16,000 from donors linked to The PMA Group, Visclosky campaign spokesman David St. John said Wednesday.

"There's been questions raised about some contributions," St. John said. "Having seen the allegations, the congressman decided to turn that money over to the Treasury."

Reports surfaced last week that the FBI raided the Virginia-based offices of the powerful PMA Group in November.

The firm -- which works with defense contractor clients -- has been Visclosky's biggest single source of campaign cash since 2003, funnelling $179,450 to him since 2001.

Visclosky reportedly will return donations given in the last two election cycles by John Pugliese and Jon Walker, Florida residents each listed as PMA associates.

"It was presumed, based on the campaign, that these were PMA employees and that these were legal contributions," St. John said. "The information coming in did not set off a red flag or signal back then. In light of new information coming out ... we felt it was best to return those contributions."

St. John said the campaign focused on the two men's donations after national news reports questioned whether information in their donation materials about being PMA employees was correct.

Election records show Pugliese and Walker gave Visclosky $8,000 each, in five nearly exact increments.

There was no answer Wednesday at phone numbers listed for the men at homes along Florida's northeast coast.

PMA spokesman Patrick Dorton said Wednesday both men were members of the firm's board of directors. Dorton said he had no comment on the men's contributions.

In a note filed Feb. 12 with the Federal Election Commission, Visclosky's campaign said it "mistakenly reported" a donor's employer as PMA Group. It corrects it to be Van Scoyoc Associates, another top Visclosky backer.

The campaign discovered the mislabeled data in stepped-up efforts to analyze PMA contributions, St. John said.

Though Visclosky had pledged to repay campaign cash "if any wrongdoing is proven," St. John denied any misdeeds occurred.

"It's not a question of, 'Oh, this is all wrong,'" he said. "It's just some adjustment needed to be made."

He called it "the right thing to do."

There have been no charges in the probe, and the U.S. Justice Department has declined to provide details. Visclosky has said he has not been contacted by federal authorities regarding PMA.