Obama saying a nuclear Iran is unacceptable probably had something to do with it. I'm guessing that he's still open to talking, but understands how Israel would feel about a nuclear Iran. He has to walk a tighrope between looking and sounds tough, while trying to talk Iran and Israel away from killing each other.

In short, it's great that he won, but now he has to govern, which is vastly different from running against an unpopular administration.