The Office of the President of the United States is controlled my the machinery of government. At this point, the person you put in there does one thing that we need to pay attention to: appoint judges. Everything else is just nuance of a system so entrenched, even the staunchest Green Party candidate would have problems doing anything he/she claimed as a candidate. Once the person is elected, "realism" kicks in, and the person is merely a guide on an already sailing ship.