The Democratic Congressional Campaign Committee is going up with a radio ad hitting Rep. Vern Buchanan for his connection to a defunct car dealership that the Federal Election Commission accuses of funneling money to the Florida Republican’s campaign.

“Congressman Vern Buchanan. His old business was caught illegally funneling over sixty thousand dollars in campaign donations to Buchanan to influence his election,” the ad says, according a DCCC release. “Tell Buchanan to come clean.”

The ad will run for one week on four radio stations, a DCCC spokesman told Roll Call. Earlier this month, after news broke that the FEC had filed a motion to impose a fine on a car dealership Buchanan once had a substantial financial stake in, the Florida Democratic Party called for Buchanan to resign his position as the finance vice chairman of the National Republican Congressional Committee.

A former employee at one of Buchanan’s car dealerships told Roll Call in 2008 that he had seen significant fraud and campaign finance violations at the dealership. He said that when he pushed back against the practices, he was fired.

The Buchanan campaign knocked down the DCCC ad in a statement Friday. “The Democrats are trying to deflect attention from the [Rep.] Anthony Weiner [D-N.Y.] scandal with a laughable attack against Congressman Buchanan. It was Buchanan who first reported these questionable donations to the FEC two and a half years ago,” the statement said.

“And the FEC obviously found that Buchanan had no involvement because the fine was issued against Sam Kazran, not Buchanan or the Buchanan campaign,” the statement said, referring to Buchanan’s former business partner.

Earlier this month, his office told Roll Call that the FEC fine was an issue between the agency and the dealership, which “Vern Buchanan has no interest or stake in.”