Apparently, confirmed adulterer/hypocrite David Vitter thinks that being unfaithful to one's spouse is grounds for resignation from public office. When Bill Livingston stepped down from the Speaker's role in the mid '90s because of the disclosure of his various extramarital affairs, Vitter said, "I think Livingston's stepping down makes a very powerful argument that Clinton should resign as well and move beyond this mess."
Vitter's situation isn't quite the mess that Clinton's was, but then, Clinton didn't actually pay for sex like Vitter did. You make the call.
Bonus question: If the DC Madam is being prosecuted for running a prostitution ring, and there is evidence that Vitter was one of her clients, should he be prosecuted too? Or is it simply too hard to prove he actually had sex with one of the Madam's call girls?