For the fourth season cast, producers initially considered actors like Edward Burns and Wentworth Miller for the role of Howard T. Erickson, because they were closer in age/physique to Erik Prince, the founder of Blackwater whom the season was based on. John Goodman stressed his availability, and the role was tailored to suit his style. Zelman saw Dylan Baker on stage years ago when Daniel was an apprentice at the Williamstown Theatre Festival in Massachusetts. His performance left an impression, and producers had thought about casting him several times before, but the timing didn't work out until Season 4, when he was cast as Jerry Boorman. Chris Messina at his first casting call, refused to play a Republican or a lawyer on the show, because he was repeatedly cast in such roles beforehand. He was awarded the role of PTSD-plagued Chris Sanchez and underwent considerable preparation for the role. He would "stay awake and not sleep...and right before action...drink two Red Bulls". He was also reluctant to join a show so late in its run. The role of Bill Herndon was, as with Ray Fiske or Katie Connor's, conceived as a very minor part but was significantly increased after Judd Hirsch made a good impression.