"The Republican leadership, instead of saying to its supporters around the country, 'calm down' ... they are pouring more and more gasoline on flames. And that is irresponsible. It's time that there be some adult supervision within the Republican party. That some Republican leader say, 'This is unacceptable,'" Van Hollen told MSNBC's Chris Matthews.
Van Hollen said the far right -- and its violent threats -- "is now the face of the Republican party."