But for different reasons than many Americans realise.
"Of course the President's not the king. The President's far more powerful than the king. The President has the power that kings have never had." So sayeth Dershowitz.
This is nearly true not because the American president has absolute (and thus arbitrary) power. It is nearly true because kings and queens don't have the powers Americans imagine. Most of them are subject to the law. The English royal family is.
The reason I say "nearly" is because a long, long time ago, many of them had arbitrary powers. Long before Jefferson wrote his document, the king of England lost his head over the matter.