From TV Guide's Ask Ausiello:
"Question: Let me get this straight: Most of the original cast members of The West Wing will be leaving after half of the season? — Amy
Ausiello: No, most of the original cast members will be in roughly half the episodes, spread out over the entire season."
Question: Is there even a glimmer of hope that Rob Lowe will be back on The West Wing even for one episode? — Krysta
Ausiello: If there is, it's fading fast. An NBC rep says nothing is planned at this time."
From TimeOut NY (article not available online):
"We're as surprised as you are that it took Janeane Garofalo so long to land on The West Wing. Now that its producers have her, they ain't letting go: She signed on for three episodes as Matt Santos's communications director, but will appear in at least four. Her character works overtime tonight when Republican Arnold Vinick (whom we so want to win) tries to box in Santos by making immigration a big campaign issue."
From Broadcasting & Cable:
"Actress/activist Janeane Garofalo, who co-hosts a show on liberal radio net Air America, is joining the cast of NBC drama West Wing to handle press for Democratic candidate Matt Santos (Jimmy Smits), at least for eight episodes, according to Air Amierca's Andi Parhamovich."