If history is a guide, Democrat Barack Obama will have a tough time in the first presidential debate on Wednesday, Republican Mitt Romney will be particularly aggressive, and both will risk committing a damaging gaffe if they wander off their talking points.

“They are pretty evenly matched as debaters,” said Alan Schroeder of Northeastern University in Boston, who has written a history of presidential debates. “They both tend to be more intellectual than emotional, and they are both articulate and comfortable on camera. But they would both prefer to be in a more controlled setting.”