Ann is fundamentally correct. Bush can pick anyone he wants. Anyone. Why pick someone that could slide through a Dem senate when that isn't needed? Why have uncertainty? Why not find a great 39 year old litigator doing pro-bono work for right wing causes all over the place (like the left did when they appointed Ginsburg - though she was not 39, more like 89).
http://www.freerepublic.com/focus/f-news/1446937/posts
Check this out. Seems to me Roberts is pretty solid if he voted to overturn that idiot Robetson.