US presidential candidate Donald Trump often yells at protesters to "get out" of his rallies and says that he wish he could knock them out.
Fellow 2016 US presidential candidates have criticised Mr Trump for allowing a culture of violence around his rallies, but he has not taken responsibility.
The Republican front-runner has said he missed the days when protesters would leave rallies "in a stretcher".
He has also told supporters to punch protesters. At the last Republican debate, he said he does not condone violence.