(Metairie) -- U.S. Senator David Vitter of Metairie is apologizing to his constituents after his phone number appeared on a list of clients of the DC Madame. Vitter Monday night apologized for what he called "a very serious sin" in his past. Vitter says it is something that happened before he ran for the Senate and says he has asked for forgiveness from God and his wife. Vitter says he did that through confession and marriage counseling. The counseling was well publicized, but it wasn't until now the public knew the full extent of his marital problems with his wife, Wendy. Vitter, a conservative Republican, is up for reelection in 2010. Also Tuesday, Canal Street madam Jeanette Maier told New Orleans' WDSU-TV that Vitter paid over $300 an hour for unspecified services at her New Orleans brothel. Maier would not say how many times Vitter visited, but did say it was more than once.