Obama super-PAC launches $1.25M radio push

"One hundred fifty million Americans: seniors, veterans, the disabled," the ad's announcer says. "Romney attacked them when he thought no one else was listening."

The ad then launches into an attack on Romney's tax policies and personal finances.

"Romney is a millionaire who uses loopholes to pay a lower tax rate than many nurses or police," the narrator says. "Romney’s plan makes middle-class families pay more — two thousand dollars a year — while giving multi-millionaires a tax cut of two hundred fifty thousand dollars."

The ad arrives at that claim based on a study from the Tax Policy Center that the Romney campaign has previously disputed. Romney has repeatedly defended his comments at the fundraiser, saying that while they were "inelegant," he was simply saying he didn't expect to win the votes of all Americans, but that he plans to represent all "100 percent" as president.

Nevertheless, the municipal workers' union continued to highlight the comment in a statement accompanying the ad release.

“Mitt Romney has proven he'll say anything to get elected," said Seth Johnson, AFSCME assistant political director, in a statement. "But when he thinks only his big donors are listening, the real Mitt comes out. Romney’s complete disdain for the middle class, the hard-working men and women of this country, the 47 percent, is reprehensible."