President Obama went there today, mocking opponent Mitt Romney over a 1983 incident in which he ferried the family dog atop his car during a vacation trip.

Speaking in Iowa, Obama noted that Romney criticized the usefulness of wind energy projects by saying "you can't drive a car with a windmill on it."

Ad-libbed Obama: "I know he's had other things on his car."

The joke comes shortly after the 45-second mark of the video; the president made the same comment later in the day during an event in Marshalltown, Iowa.

On the second day of a three-day bus tour of Iowa, Obama again called on Congress to extend a program of tax credits for wind energy manufacturers.

And, as he did last week in Colorado, he again criticized his Republican opponents for opposing those tax credits.

After the comments about windmills (and dogs) on tops of cars, Obama said Romney obviously doesn't know how important wind energy is to a state like Iowa.

"The wind industry now supports about 7,000 jobs in this state, and 75,000 jobs across the country," Obama said. "These jobs aren't a fad -- they're good jobs and sources of pride we need to fight for."

Romney says a better way to promote wind energy is by reducing government regulations and promoting "market-based competition" among different companies.

"Under President Obama's approach, the industry has lost 10,000 jobs while growth in wind power nationally has slowed every single year of his term," said Romney spokesman Ryan Williams.

As for the dog comment, Williams said: "After sanctimoniously complaining about making a 'big election about small things' President Obama continues to embarrass himself and diminish his office with his unpresidential behavior."

Earlier this year, Romney's wife Ann told ABC News that the family pet Seamus "loved" the trip back in 1983.

"He would see that crate and, you know, he would, like, go crazy because he was going with us on vacation," Mrs. Romney said. "It was to me a kinder thing to bring him along than to leave him in the kennel for two weeks."