Tired of all those political ads on your TV screen? Don't look to your radio for relief.

Radio ads are an important component of a presidential candidate's media strategy. Listeners are being bombarded in battleground states in much the way such political commercials are swamping 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. Still, that's 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.