Click here to watch "License."

It's less than three weeks before Election Day and the economy continues to dominate headlines, propelling Barack Obama's gain over John McCain in the polls. What's a conservative group to do? One PAC is turning to perhaps the only topic that could tear both voters and the media away from the financial crisis: the terrorist attacks of Sept. 11.

The National Republican Trust PAC started running an ad, "License" (subscription), in Ohio on Thursday that uses images of a burning World Trade Center and hijacking mastermind Mohammad Atta. The spot notes that many of the 9/11 hijackers were able to obtain driver's licenses and claims that Obama's support for allowing states to issue licenses to illegal immigrants would endanger the nation's security.

"Nineteen terrorists infiltrate the U.S." the ad's announcer says. "Thirteen get drivers licenses. The 9/11 plot depended on easy-to-get licenses." Images of Obama and of the smoke- and fire-filled towers follow one of Atta's face on a Florida driver's license while the announcer asserts, falsely, that "Obama's plan gives a license to any illegal who wants one." The ad goes on to tie its central claim about national security to hot-button issues such as the housing crisis and voter fraud, warning that illegal immigrants with licenses could "get government benefits, a mortgage, board a plane, even illegally vote."

The issue of whether or not to grant licenses to illegal immigrants -- and, for that matter, the subject of immigration in general -- has hardly come up during the general election. It played a far larger role during the primaries, when Republican candidates accused each other of favoring "amnesty" and Democrats sparred over the licensing issue.

While the amount of the ad buy has not officially been confirmed, the Politico dug up FEC fillings that show the group has spent $200,000 opposing Obama. How much of that is tied up in this ad is unclear. The group also sent out e-mails making the same claims as the ad does, while also alerting supporters of the plans to release the spot. It's reportedly running in Ohio, with potential plans to run it in more states.