Sen. David Vitter (R-La.) has earned a ranking member slot on an Armed Services subcommittee, thanks to the seniority shuffle that has shaken out in the wake of Sen. Arlen Specter’s (Pa.) recent party switch.Vitter, a first-term Member up for re-election next year, will become ranking member on the Subcommittee on Strategic Forces, a post most recently held by Sen. Jeff Sessions (R-Ala.). Sen. Bill Nelson (D-Fla.) is chairman of the subcommittee.Sessions, the newly installed ranking member of the Judiciary Committee, had to forfeit his subcommittee chairmanship under Senate Republican Conference rules.