It’s pretty obvious, as one of the background speakers in this video points out, that had this kind of behavior been exhibited by a Republican, it would have been all over the nightly news. The perpetrators would be likely to have been arrested, given this kind of behavior in front of watching cops. But here we have some out of control anger, expressed by tearing down signs and shouting obscenities at peaceful Republican campaigners, who are simply sitting on their own property holding signs in support of their candidate.
UPDATE:
Intelligent commentary on the “racist” hypothesis as an explanation of Republican sentiment.