A person who, by nature of their status or job, expesses their views in mass media without attempting to back up their assertions. Usually their assertion includes fairly incindiary accusations against someone or some political position they do not like. In other words, they make up something and say it on the air or in print with no proof or at best, very poorly constructed reasoning. These people can be professionally paid to provide opinions or simply be trying to push public opinion away from their political opposition.
Well-known Opinion-slingers: Rush Limbaugh, Glenn Beck, Keith Olbermann, Bill O'Reilly, Rachel Maddow, Joe Scarborough, Chris Matthews, Sean Hannity, Sarah Palin, Tom Delay, Ralph Nader