A National Republican Congressional Committee-recruited House candidate filed court papers Thursday in Canton, Ohio, accusing a prominent labor union of launching a smear campaign against him and his family.

Republican businessman Jim Renacci is locked in a competitive race against freshman Rep. John Boccieri (D), who won the manufacturing-heavy eastern Ohio district in 2008 after decades of GOP control.

On Thursday, Renacci sued the American Federation of State County and Municipal Employees for allegedly defaming his character in a recent round of television ads that cost the union $750,000. As of midday Thursday, a copy of the lawsuit was unavailable, but in one recent AFSCME television ad aired in the district the union claims the GOP candidate “cheated on his income taxes.”

“Renacci hid $13 million and was forced to pay $1.4 million in back taxes and penalties,” the ad’s narrator says. “What do you think?”

In a statement, Renacci denied the accusations, reiterating repeated claims that no one in his family has ever “been subject to any kind of criminal charge or criminal investigation of any kind.”

“In a desperate attempt to hide from his record of support for every component of Nancy Pelosi’s agenda in Washington — including Cap and Trade and rampant fiscal recklessness that has crippled our economy and wiped out our jobs, John Boccieri and his allies are engaged in a scorched earth assault on me, my family and the truth,” he said in the statement released Thursday, referencing Speaker Pelosi (D-Calif.).

Earlier this month, FactCheck.org chided AFSCME for running the series of television ads it determined “badly misrepresents [Renacci’s] stance on taxation.”

“AFSCME’s ad says Republican challenger Jim Renacci ‘supports a 23 percent national sales tax,’ and then shows 10 men and women reacting by calling it a bad idea and an unacceptable threat to a struggling middle class,” the nonpartisan website reported. “It’s true enough that Renacci has voiced support for the so-called ‘FairTax’ proposal, which is billed by supporters as a 23 percent tax on sales. What the ad fails to mention is that the FairTax would replace the federal income tax and abolish the Internal Revenue Service, according to its supporters.”