Thompson says the radio is a natural fit for someone who grew up listening to AM broadcasts, including the well-known commentator Paul Harvey. In fact, the former Tennessee senator is quick to point out he filled in for Harvey for a while.
"I wanted to bring it back in this campaign," Thompson said.
"It's worked out real well for us."
With a deep voice and Southern drawl, Thompson shows off a radio host's knack for chatter, touching on issues that interest listeners and give him a chance to swipe at opponents: -Illegal immigrants will leave the U.S. if they cannot find jobs or sanctuary - a dig at former New York Mayor Rudy Giuliani.
-School vouchers are good. Rival Mike Huckabee won the endorsement of New Hampshire's National Education Association, a state affiliate of the nation's largest teachers' union, in that state's primary because he opposes vouchers.
-It is not known what is behind global warming, so the U.S.
should not stake its economy on fixing the problem, certainly not without China and India doing the same.
-Compact fluorescent light bulbs may save energy, but their mercury is a health threat. General Electric, a maker of the bulb, says there is more of a health threat from being cut by broken glass from the bulbs than from the small amount of mercury in them.
With the radio's mike on or off, Thompson sends mixed signals about the race.
"This is serious business about serious things," Thompson tells crowds, saying the media's caught up in personality clashes and "other stuff, but I'm not."
Thompson said at a Lady's Island restaurant on Saturday that "it's not my nature and it's not my mission to jump anybody."
But in a couple of breaths, he makes it clear he is the scrapper in the South Carolina race, going after favorite target Huckabee for advocating a national smoking ban in public places and wanting to shut down Guantanomo Bay.
Then it is back to complaining about how the fight for the nomination progresses. "It's not about attacks or being attacked or quips or who gets off the best line," Thompson says. "It's hard to get a good discussion going on a serious issue."