From TV Guide:
"Former cast member Rob Lowe returns as a senior political official in this episode, which finds Bartlet and his staff making the transition as easy as possible for the president-elect, who discovers some unpleasant realities about his new job. Meanwhile, a stressed-out Josh realizes that he may need to take some time off after he reaches his breaking point. Nancy McNally: Anna Deavere Smith."
Cast Listing: Martin Sheen, Allison Janney, Bradley Whitford, Janel Moloney, Lily Tomlin, Jimmy Smits, Rob Lowe, Teri Polo, Janeane Garofalo, Anna Deaveare Smith, Karis Campbel, Ramon De Ocampo, Ashlyn Sanchez, Joshua Cabrera, Matthew Del Negro, Renee Estevez