You give Talk Radio far too much credit. At best, one or two out of every 100 citizens listen to Talk Radio. And most of them are already in agreement, so that talk radio hosts are mostly only preaching to the choir.
The biggest problem is voter apathy on the part of the few who do vote, and massive voter fraud on the part of dead Democrats.
Someone who has access to the surveys and other industry documents of audience behavior will have to respond to the accuracy of your one or two out of 100 comment. I don't know those facts, I don't have access to those facts.
Here is what I do know. I live in the "political petrie dish" of a community where 'Appalachia in Overalls" co-exists with "Big Shots driving Bimmers" and guys taking chickens for their last ride over to the Tyson Plant co-exist with the Olive-skinned folks who came here from nations around the world to get their education and now they work in those hi-tech places in what amounts to Georgia's version of Silicon Valley.
And as I stop somewhere to eat lunch, as I bop into McCafe for a mid-afternoon cup of coffee, as I sit and wait while the pharmacist refills my truck-load of prescription bottles, I listen to the conversation around me. I engage people in direct conversation. (One of my children famously proclaimed one day: "My Dad will carry on a conversation with a fireplug.... if he can find one that talks." Now some of these people (most of these people?) didn't listen to the radio. They picked it up from someone at their last coffee stop, some one in the truck dispatch office as they started their day, from their fishing buddy as they went bass fishing in synch with the moon about 11 P.M. last night... an amazingly large percentage of the population is sharing with me the word-for-word gospel of Limbaugh and Hannity. Little country church preachers are apparently listening to Limbaugh for enhancements for their next sermon when they ought to be in a seminar down in Atlanta getting resources from a traveling seminary professor.
People who don't even know where to tune in Talk Radio.... are quoting Talk Radio to me and lecturing me on the proper pattern for voting.
And you just did it with your comment about "massive voter fraud on the part of Democrats." Straight out of the Talk Radio playbook. How many cases of voter fraud by either party have been brought to court in the last five years in this state you and I share as a place of residence.