A real live ‘Loose Cannon’!
An unpredictable person or thing, liable to cause damage if not kept in check by others.
From the 17th century to the 19th century, wooden warships carried cannon as their primary offensive weapons. In order to avoid damage from their enormous recoil when fired they were mounted on rollers and secured with rope. A loose cannon was just what it sounds like, that is, a cannon that had become free of its restraints and was rolling dangerously about the deck.
This guy is so far over the top that the Tea Party fear him.