Nevada Sen. John Ensign (R) continues to face questions about an extramarital affair as he begins his uphill reelection campaign.

Ensign's poll numbers have taken a hit since he admitted in June 2009 to having an affair with the wife of one of his top aides. Speaking to about 60 seniors in Sun City on Tuesday, Ensign was asked if he'd "repented to God for [his] affair?"

Ensign told the audience he had repented to "my Lord ... but also to my family and to anybody else that I hurt."

The two-term senator knew the question was coming but said he didn't want to "duck it."

"It's something I will regret for the rest of my life," he said, according to the Las Vegas Review Journal. "If I could ever take back anything that I've ever done, this is it."

Despite the affair and an investigation by the Senate Ethics Committee for allegedly helping his aide, Doug Hampton, land work as a lobbyist, Ensign is gearing up to seek reelection. To do that, he'll need to win over his skeptical supporters and convince his donors he can win. Ensign said he plans to raise $12 million for his reelection effort.

"I would not run if I did not think I could win," he said. "Experts have written me off before."

His first obstacle will be a Republican primary, where he's likely to face at least one strong challenger.

But Ensign had only positive things to say about Rep. Dean Heller (R-Nev.), potentially his strongest challenger. "If Dean Heller runs, that's his own business," he said. "I think Dean's done a good job as a member of Congress, and I said that at every Lincoln Day dinner I did this weekend."

Meanwhile, Democrats may be looking beyond Rep. Shelley Berkley (D-Nev.) to find a nominee.

Guy Cecil, executive director of the Democratic Senatorial Campaign Committee, was in Nevada this week meeting with Secretary of State Ross Miller (D), Treasurer Kate Marshall (D) and Attorney General Catherine Cortez Masto (D).