Republican frontrunner Donald Trump had to call off a rally when violence erupted between his supporters who had come for the rally and anti-Trump protesters who were protesting against Mr Trump at the scene.
Democracy is best practiced not by use of violence to determine a decision, but by respect of the will of the voters.
For more details and photos of the violent clashes click this article I linked to: Trump calls off Chicago rally following violent clashes – BBC News
He did the right thing.
Violence is not an option in democracy.