"Kerry doesn't try that many jokes because it's not really natural to him," Schroeder says. "You can see the gears sort of turning when he's trying to do one of these things that he's been told to do. … He can't make it sound like it's something he just thought of."
"Bush's issue is sort of that he's so on message, you don't feel like you're getting the answer to the question," Schroeder adds. "You're getting the answer that he rehearsed."
ABC News' Terry Moran contributed to this report.