Though Democratic U.S. Rep. Tim Mahoney did not directly mention allegations first reported by ABC News that he had been involved with the former aide, he issued a statement apologizing to his family but denying he'd done anything illegal.
Later Tuesday, a person close to his campaign told The Associated Press that Mahoney also was having an affair with a second woman around the same time.
Mahoney, 52, won his seat in 2006 while promising to return morals and family values to Washington in the aftermath of the resignation of former Republican U.S. Rep. Mark Foley. Foley stepped down when it was revealed he sent lurid Internet messages to male teenage pages who had worked on Capitol Hill. Foley was later cleared of criminal wrongdoing by state and federal authorities.
Mahoney's seat was already considered to be one of the more competitive House races, and he has been facing a tough challenge in a district that traditionally leans slightly Republican. He faces former Army officer Tom Rooney, a lawyer whose family owns the Pittsburgh Steelers.
During the news conference, before details of the second purported affair surfaced, Mahoney 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."
He said he never misused campaign money and was confident he will be cleared of wrongdoing.
Mahoney's statement came one day after ABC News reported that he had an affair with an aide and then paid her $121,000 to keep her quiet and avoid a sexual harassment lawsuit. After the report, Mahoney called for an investigation into his own conduct by the House Ethics Committee. House Speaker Nancy Pelosi also called for an inquiry.
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. Allen has not returned repeated telephone calls from The Associated Press.
On Tuesday night, a person close to the Mahoney campaign told the AP that Mahoney also was having a relationship with a high-ranking official in Martin County in his Florida district around the same time of the purported affair with Allen.
The person close to the campaign spoke only on condition of anonymity because he was not authorized to openly discuss Mahoney's private life.
The person said Mahoney was having the relationship with the official in 2007 while he also was lobbying the Federal Emergency Management Agency for a $3.4 million reimbursement for Martin County for damage caused by hurricanes in 2004. FEMA approved the money late last year.
Mahoney's congressional staff declined to comment on this alleged tryst, but noted Mahoney lobbies for FEMA funding throughout his district, and that Martin County has received $43 million from FEMA since 2004. Mahoney didn't take office until 2006.
Meanwhile, a high-level Democratic operative who has been involved with the Mahoney campaign told the AP on Tuesday night that the FBI has begun reaching out to attorneys involved in the initial reported affair and accusations that he paid the woman to keep quiet. The person declined to be identified because of the FBI's involvement.
A telephone message left late Tuesday night on Mahoney's cell phone was not returned.
Republicans seized on the Allen scandal earlier in the day.
"We're pleased that an ethics investigation has been called for but quite frankly, we're not going to know the answers in three weeks unless Congressman Mahoney literally sits down ... and answers some questions," said Rep. Tom Cole of Oklahoma, the chairman of the National Republican Congressional Committee.