[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/images/08/21/art.mccainad.cnn.jpg caption="McCain is out with a new ad."](CNN) - On the heels of an aggressive effort by the Obama campaign to exploit John McCain's recent inability to recall how many houses he owns, the Arizona senator's campaign is launching a new television ad slamming Obama over his dealings with disgraced Chcago businessman Tony Rezko.
"Barack Obama knows a lot about housing problems," the 30-second ad's announcer states. "'One of his 'biggest fundraisers' helped him buy his million-dollar mansion. Purchasing part of the property he couldn't afford."
"From Obama, Rezko got 'political favors' including '14 million from taxpayers,'" the narrator also says. "Now, he's a convicted felon, facing jail."
The McCain campaign said the ad will air in "key states." Earlier Thursday, Obama's campaign released a housing ad of their own referencing his inability in a Politico interview to name the number of properties he and his wife own.