Pro-Romney super-PAC goes back on air in Michigan, Wisconsin

The ad is the first the group has run in either state for more than three weeks. Both Romney and President Obama have been spending in Wisconsin in recent days, but in Michigan neither the Romney campaign nor Obama and his allies have spent much on commercials.

That could change: Polls show Michigan tightening a bit, with a Democratic poll released earlier this week showing Obama up just 2 points in the state and a Republican poll showing the president with a 6-point lead.

Polls suggest Obama is pulling away from Romney in some other swing states, including Ohio and Virginia, and these two states seem the best chances for Romney to make up ground elsewhere on the map.

The ad features a clip of CBS News's Scott Pelley saying "this is the worst economic recovery we've ever had" — one that's been featured in a number of GOP ads against Obama, and argues that the economy is doing even worse than the unemployment rate indicates.

"Millions of Americans are disappearing from the workforce because they can't find jobs. The overall unemployment rate doesn't even count them anymore," the ad's narrator says. "Eight million Americans have dropped out of the workforce since Obama became president. Counting people who dropped out or can't find full-time jobs, the real unemployment rate is nearly 19 percent."