Obama has failed at leadership because as a president, he should be able to convince Congress that his actions are just. If he can't do that (which he hasn't), then that's just tough beans.
Each presidency we see more and more power being either given to the president or the president takes. Eventually, we will have a dictator if it keeps following this trend. I don't think Obama is a dictator, however, I do think he's crossed the lines of what I find acceptable behavior. And it will only get worse each presidency at this rate.