In key battleground states, huge numbers of presidential ads are airing on TV stations that are not required to post to the Federal Communications Commission's online political ad database, new data released by the Wesleyan Media Project shows. 

Beginning Aug. 2, the FCC required television stations affiliated with the top four networks (ABC, CBS, Fox and NBC) in the nation's top 50 television markets to upload new political ad purchases to a public database. But that leaves out some 160 television markets, some of which are in battleground states. The numbers captured by CMAG in non-disclosing markets show that the rule in place misses a lot of the spending in the presidential race. 

In four of the nine states considered key in this year's general election — Colorado, Florida, Virginia, Ohio, Nevada, New Hampshire, North Carolina, Virginia and Wisconsin — less than half of presidential ads would be disclosed on the FCC database, a Sunlight analysis reveals. 

Based on ads that ran from Sept. 9 through Sept. 30:

• Iowa saw 17,000 presidential ads; none of its eight television markets are covered by the FCC order. 
• In Wisconsin, 70 percent of the ads recorded aired outside of the top 50 markets. Only the four Milwaukee network affiliates are required to post to the FCC online database. Spending in the state has increased dramatically over the last month. 
• Fifty-five percent of ads in Colorado would not be disclosed to the FCC.
• Of New Hampshire's 7,000 ads, slightly more than half have been run in uncovered markets. 

Because of the shortcomings of the FCC rule, Sunlight, along with our partner Free Press, is rolling out Political Ad Sleuth in an attempt to capture what the FCC rule leaves out. You can find out more about the project, including how you can help us free political ad files, by clicking here.