The Service Employees International Union (SEIU) which represents 1.5 million public service workers, nurses, hospital staff, nursing home care providers, building services and security guards, in North America has released an ad on behalf of Senator Obama attacking Senator McCain over his lack of knowledge on economic issues. The ad is a 30 second spot.
Other unions are also coming to the rescue of the Obama campaign but at this point my guess is that 527 groups ads are running by a four or five to one margin in favour of McCain.