Louisiana Sen. David VitterDavid VitterMercury brings on former Sen. Vitter, two others Lobbying World Bottom Line MORE again confessed he had committed "serious sins" but said the "strong forgiveness" he received has allowed him to carry on and seek reelection.

Host Norman Robinson opened the first Senate debate with a question about how family values influence the candidates' conduct. After talking about his grandson, Democrat Charlie Melancon aimed an opening salvo at Vitter's character. 

"It's about honesty and integrity in Washington," the congressman said, echoing the words of independent candidate Mike Spears, who was among the six participants in the debate. "And that is one of the key ingredients and the reason why I think everyone got into this race to challenge Mr. Vitter."

The debate, broadcast from the studios of WDSU-TV in New Orleans, was the first meeting between Vitter and Melancon. It was also the first time Vitter had appeared in a TV debate since his Senate career was marred by a personal scandal in 2007 when his telephone number appeared in the phone records of the "D.C. Madam."

The calls were dated from before his run for Senate in 2004. He issued a statement apologizing for committing a "serious sin," but never elaborated.

His remarks Wednesday night were equally circumspect. 

"Obviously, I've stumbled in my marriage. And obviously, I've committed serious sins, which I've talked about in the past," Vitter said in his opening statement. "Having come through that experience and received that strong forgiveness, it's really strengthened me and redoubled my focus on living true to those values and commitments and living true to the values and wishes of the people of Louisiana."

As the debate continued, state lawmaker Ernest Wooton (I) had some of the harshest exchanges with Vitter. He questioned why the senator's former aide, Brent Furer, remained on staff for two years after being arrested on suspicion of assaulting a female friend with a knife and threatening to kill her.

Furer later pleaded guilty to lesser charges. 

Vitter only fired him after ABC News reported Furer had a lengthy rap sheet that included arrests for cocaine possession and drunken driving. 

Vitter said he suspended Furer but did not fire him initially "because there were very difficult stories from both sides, domestic violence incident with serious charges between girlfriend and boyfriend." 

Wooton pressed the issue.

"You paid the man for two years after he pled guilty to three misdemeanor charges against women," he said. "He stabbed her ... big scar under her neck ... he choked her. What do you say to that?" 

Vitter said Wooton was distorting the facts. "Look at the facts, because what you just said is untrue."

Wooton: "He didn't plead guilty to three misdemeanor charges?"

A shaky moment for Melancon came during a lightning round when the candidates had to answer only "yes" or "no" to questions.

Asked whether America was risking "another Vietnam" because of the Obama administration's policy in Afghanistan, Melancon said he was "ambivalent" before answering "no," according to the New Orleans Times-Picayune. Vitter said "no."

Melancon and Vitter meet Thursday in a second debate.