You're right and wrong. The country was set up so that Congress would have most of the power, but as much as people like to ignore it the Office of the President has changed as much in its role as much is it has in its staff. Teddy Roosevelt was the first guy to campaign for a much more aggressive presidential reign, and he did it without much support in Congress, which he despised. From what I've heard, Bush thought that the POTUS didn't have enough power and that a strong U.S. needed a strong leader, and therefore would take a strong stance, whatever the cost, to reassert Presidential superiority over Congress.