Democratic U.S. Rep. Tim Mahoney on Tuesday admitted causing "embarrassment and heartache" in his marriage but denied paying hush money to a former aide to be quiet about an affair.

He did not directly address the purported tryst, but instead issued a statement taking "full responsibility for my actions and the pain I have caused my wife Terry and my daughter Bailey."

"No marriage is perfect," Mahoney said, "but our private life is our private life, and I am sorry that these allegations have caused embarrassment and heartache."

The statement came one day after ABC News reported on its Web site that Mahoney had an affair with an aide and then paid her $121,000 to keep her quiet and avoid a sexual harassment lawsuit.

ABC, citing unnamed current and former Mahoney staff members, said the congressman began his affair with Patricia Allen, 50, in 2006 while he was campaigning for Congress, promising to return morals and family values to Washington.

Mahoney, 52, won the race after former Republican U.S. Rep. Mark Foley resigned when it was revealed he sent lurid Internet messages to male teenage pages who had worked on Capitol Hill. Foley was cleared of criminal wrongdoing by state and federal authorities.

Mahoney and House Speaker Nancy Pelosi have called for an investigation into his own conduct by the House Ethics Committee. Mahoney said he will be vindicated.

"I want to be clear that I have not misused campaign funds and I'm confident that when all the facts come to light, I will be cleared of any wrongdoing," he said in the statement. "I have not violated my oath of office, nor have I violated any laws, and I consider this to be a private matter."

Mahoney's bid to earn another term representing a district that has traditionally leaned slightly Republican was already considered one of the more competitive House races this fall.

He faces a stiff challenge from former Army officer Tom Rooney, a lawyer whose family owns the Pittsburgh Steelers. Rooney is mounting a well-funded race aiming to win back the district for Republicans.