All he needs is a riot or a war and a pen. Or simply a pen and say that for the good of the country he cannot allow the United States to fall back into the hands of those who will bring back the failed policies of the past which resulted in the problems we face even still today.
The people will accept it. It will sound good and sophisticated so it must be true. After all, that's all they went by when they voted for the guy the first time.