Sen. David Vitter (R-La.) has done a pretty good job salvaging his political career after his phone number surfacedlast summer among those kept by the leader of a reputed prostitution ring. His method has been simple: Apologize for “a very serious sin,” and then discuss it never again. But that silence might soon be broken — by subpoena. The Associated Press reports todaythat Vitter — who has rested his career on a platform of family values — was listed among the potential witnesses in the case against Deborah Palfrey, the alleged leader of the prostitution ring. Vitter’s Web site trumpets his dedication to “advancing mainstream conservative principles.” If he is compelled to testify in the Palfrey case, that bio may require a quick edit.