The West Wing star John Spencer, who played Leo McGarry, died today in a Los Angeles hospital of a heart attack, according to his publicist. Spencer played Chief of Staff to Martin Sheen's President Jeb Bartlet. On the show, ironically, Spencer's character suffered a heart attack that forced him to give up his White House gig. In a main storyline this season, though, his character had been tapped as a vice-presidential running mate for Democratic hopeful Matt Santos, played by Jimmy Smits.