I guess I've seen too many of these movies, where an ordinary guy is switched with a leader (think "Dave"), and has to pretend to be the leader. During that process, he turns out to be a more compassionate and effective leader than the original dude. And of course, somehow pulls a switch at the end so that he can return to his normal life, wiser and secure in the knowledge that only he knows that a switch was ever made.
I do agree that Raul Julia is a fine actor. Watching him in this made me want to pop in "Presumed Innocent", where he does a magnificent role as a defense attorney.