Sen. John Ensign acknowledged Tuesday that he had an affair with a campaign staffer - an admission that stunned his colleagues, hurt his chances for the 2012 Republican presidential nomination and called into question his future as a leader of the Senate GOP.
The Nevada Republican admitted in Las Vegas Tuesday that he had "violated the vows" of marriage by having an affair with a staffer. He did not identify the woman except to say that she and her husband were both "close friends" who worked for him, and that "the closeness" of their relationship had "put me in situations which led to my inappropriate behavior."
But current and former aides to the Nevada Republican say the woman was 46-year-old Cynthia Hampton, a campaign staffer whose husband was a top aide in Ensign's Senate office.
"It was known in [Ensign's] inner circle that they were involved," a former aide told POLITICO.
Hampton served as the treasurer for Ensign's reelection campaign and for his leadership fund, Battle Born PAC. According to people familiar with the matter, Ensign's affair with Hampton took place between December 2007 and August 2008. FEC records show that she ended her affiliation with the two committees in early 2008.
Hampton is married to Douglas Hampton, who, according to Senate records, served as Ensign's administrative assistant in his personal office from November 2006 to May 2008 - around the same time Cynthia Hampton left Ensign's committees.
A call to the Hamptons' Las Vegas home Tuesday night was not returned; in a statement, Ensign's wife said the situation has "been difficult on both families."
Douglas Hampton was paid about $101,000 in 2008 and $144,000 in 2007 as Ensign's administrative assistant. But a financial disclosure form he filed in 2007 and 2008 - required for senior congressional staffers - showed only checking and savings account worth a maximum $30,000 combined.
A review of public records shows that the Hamptons in 2006 took out a $1.2 million mortgage on their Las Vegas home, at an interest rate of 8 percent.
Political insiders in Nevada and in the Senate said that Ensign decided to acknowledge the affair publicly after the husband of the woman he had been seeing asked him for a substantial sum of money.
Ensign described the affair Tuesday as "the worst thing I have ever done in my life."
"If there was ever anything in my life that I could take back, this would be it. I take full responsibility for my actions," he said.
Ensign said he deeply regretted the affair - and that he remains committed to his Senate duties.
Sources said Ensign strayed while he was separated from his wife. The two have since reconciled. And in a statement to the Las Vegas Sun Tuesday, Darlene Ensign said: "Since we found out last year, we have worked through the situation, and we have come to a reconciliation. This has been difficult on both families. With the help of our family and close friends, our marriage has become stronger."
Ensign informed fellow Nevadan Harry Reid, the Senate majority leader, about his situation prior to making his public announcement.
"I don't know the details. I talked with him today," Reid told POLITICO Tuesday afternoon. "Of course, he's my friend. This is a private, family matter. I just hope that Darlene and he work things out."
Reid said he didn't offer any advice on how to handle the situation. "I didn't give him any advice," he said. "I just told him he's my friend. I'm pulling for him. Anything I can do to help, let me know."
Rumors of the affair circulated through the Capitol Tuesday in the hours before Ensign made his announcement. Republican senators were stunned by the news, and Ensign's future as chairman of the GOP Policy Committee - the No. 4 job in the GOP Senate leadership - was expected to be a topic for discussion among senators Wednesday.
Elected in 2000, the 51-year-old Ensign has moved up the leadership chain in the Senate. As chairman of the National Republican Senatorial Committee in 2008, Ensign oversaw the devastating losses by GOP candidates. But his party largely spared him of blame, casting it instead on an unpopular president who dragged down the party's brand. Since then, Ensign has sought to articulate conservative principles and is a mainstay at GOP news conferences deriding Democrats' domestic policies.
A staunch fiscal and social conservative, Ensign has been considered a rising star in his party, recently making headlines by speaking at events in Iowa, raising speculation about his interest in a run for the GOP presidential nomination in 2012.
A born-again Christian, Ensign has been a member of the Promise Keepers, a male evangelical group that promotes marital fidelity.
When former Sen. Larry Craig (R-Idaho) was arrested in an airport men's room in the summer of 2007, Ensign was among Craig's toughest critics, saying Craig should step down because he had been charged with a crime.
"I wouldn't put myself, hopefully, in that kind of position, but if I was in a position like that, that's what I would do," Ensign told The Associated Press at the time.
During the 1998 impeachment of President Bill Clinton, Ensign, then a Senate candidate, called on Clinton to resign.
Written by Manu Raju and John Bresnahan
Alexander Burns contributed to this report