Obama's likeness was much more difficult to capture than Arnold's. He's got a lot going on in the shapes of his mouth that are so important to his likeness. The ears are an obvious choice but everyone does that. This was an hour's worth of drawing and week's worth of research.
Arnie really is a handsome dude. The first two are the practice drawings where I couldn't quite get the likeness. The last image is a 20 minute sketch done after 2hrs of trying to get it right.