ST. PETERSBURG, Fla. (October 26, 2012)--Radio ads are an important component of a presidential candidate's media strategy and listeners are being bombarded in battleground states in much the way such political commercials swamp television.

The campaigns and allied independent groups have spent some $20.8 million on radio so far, much less than the $1 billion they are projected to pour into TV ads.

But that’s still a healthy investment in boosting turnout among a campaign's most loyal supporters.

Campaigns tend to deliver tougher, more specific messages through radio than they do in television ads, which reach wider audiences.

Both presidential campaigns are advertising heavily on adult contemporary stations to reach women, the most coveted group of voters.