According to The Spot (a blog about political ads by the Campaign Media Analysis Group, a division of TNS Media Intelligence), special interest groups are girding up to release TV spots in targeted states. These 527 and PAC groups may "prove to be a significant force, largely because they are more willing than candidates to include incendiary information and images in their ads," states the blog.

In the last week, these groups distributed ads that focused on abortion, rape, Obama's association with Tony Rezko, Jeremiah Wright and William Ayers, McCain's bouts with cancer, and more.

Planned Parenthood, the Committee for Truth in Politics, the California Nurses Association, and the Judicial Confirmation Network sponsored ads that ran over 1,000 times during the week—costing almost $375,000.

Here are two of the ads: