For Seamus? President Barack Obama unleashed a sharp attack on Mitt Romney over his opposition to a wind-power tax credit popular in Iowa—and linked to it a long-ago incident in which the Republican candidate put his family dog, Seamus, in a carrier strapped to the roof of his car.

"We're at a moment right now when homegrown energy, like wind energy, is creating new jobs all across Iowa and all across the country," Obama told an estimated 852 people in Oskaloosa, Iowa.

The president underlined that Romney does not want to renew the tax credit when it expires at the end of the year, and painted the Republican candidate as an enemy of alternative energy.

"He's said that new sources of energy like wind are 'imaginary.' His running mate calls them a 'fad.' During a speech a few months ago, Gov. Romney even explained his energy policy this way: 'You can't drive a car with a windmill on it,'" he said.

"I don't know if he's actually tried that—I know he's had other things on his car. But if he really wants to learn something about wind, all he has to do is pay attention to what you've been doing here in Iowa," the president said.

Other things on his car? The only well-known thing Romney has had atop his car was Seamus, the Irish setter. That June 1983 family trip has become the stuff of legend in the 2012 campaign (in the Republican primaries, Romney rivals Newt Gingrich and Rick Santorum both used the tale as ammo against the former Massachusetts governor).