Campbell is one of three members of Congress who have been referred by the OCE to the larger Ethics Committee. The others are Reps. Joseph Crowley (D-N.Y.) and Tom Price (R-Ga.).
Fundraisers by all three in December were around the time the House voted on its version of the final financial reform bill, the Los Angeles Times reported. President Obama signed a final version of the bill into law in July.
The Times cited an OCE letter to one Congressman that said there could be an ethics violation for simply giving the appearance "that special treatment or access was being provided to donors or the appearance that contributions were linked to an official act."
Campbell and Price both voted against the legislation that increased oversight of the financial industry and installed more protection for consumers. Four of Campbell's top five donors this campaign cycle are in banking, investment or business, campaign donation records show.
"As one of Congress' most outspoken critics of the earmark system and the waste and corruption it engenders, I have worked to make Congress more transparent and accountable to the American taxpayer," Campbell said. "Any suggestion to the contrary is baseless and unfounded. I look forward to a favorable resolution in this matter."
Price was not immediately available for comment.
Crowley's office issued a brief statement: "Congressman Crowley has always complied with the letter and spirit of all rules regarding fundraising and standards of conduct."