Re: pushover
Primarily Obama is an academic, from a liberal academic environment. The mindset is of someone who believes that reality is a matter of consensus, and that you can talk anybody into anything. This doesn't often work in real life, and in foreign policy, it results in "speaking softly" while carrying no stick at all.
As for the rest, look at his actual biography and background.
P.S. Not to put too fine a point on it, but if you look at the current situation in Russia, China, the Middle East, Iran, and the rest, Obama has already BEEN "pushed over."