"The decision to cancel it was made before actor John Spencer, who played former presidential chief of staff Leo McGarry, died of a heart attack Dec. 16, said Kevin Reilly, NBC entertainment president."
"Producers are negotiating the return of Rob Lowe, the early series star who left because he was upset by his diminished role, for the finale...."
http://abcnews.go.com/Entertainment/...d=true&ad=true
I figured it would be Lowe to be the new VP canidate when Spencer died, not like he has much work since his 2 shows bombed.