The spot, produced independently of Illinois Democratic Sen. Barack Obama's presidential campaign, financed by the liberal activist group MoveOn.org and the American Federation of State, County and Municipal Employees, features a young mother with a baby criticizing McCain's determination to keep troops in Iraq. It began airing Tuesday in Ohio, Wisconsin and Michigan, USA Today reported.

Pro-Democrat labor union leaders told the newspaper they have assembled millions of dollars for so-called independent group advertising. The AFL-CIO said it has raised $53.4 million for the presidential and congressional elections and will enlist more than 250,000 volunteers to get out the vote. Meanwhile, the Service Employees International Union plans to spend $80 million on presidential and congressional elections, Secretary-Treasurer Anna Burger said.

The newspaper reported its analysis indicates outside "independent" groups have spent more than $25 million since Jan. 1, 2007, with more than 70 percent going to support Democratic candidates.