Is Donald Trump a bully?

In my opinion he behaves like one but gets away with it because, his primary opponents simply don't have the gumption to confront him. What does this says about these guys ability to confront a bully like Putin or anyone else for that matter, should they be one day in the Oval Office? Nothing positive or reassuring.

These candidates behave as if they had no backbone and let Trump run wild over them. If Donald makes it to the Republican nomination, how will Hillary or Bernie respond to him? This will be an interesting issue to watch unfold. I would venture to predict that our bully will have a harder time with the old man than the smart lady. Well, time will tell and anyway, we aren't there yet!