President Obama offered an earthy rural metaphor to blast Mitt Romney last night in Iowa, saying the Republican candidate offered voters "a cowpie of distortion" in a recent speech.

"I don't know whose record he twisted the most," Obama said. "Mine or his."

Speaking to supporters at the state fairgrounds in Des Moines, Obama said that during Romney's last visit to Iowa he exaggerated the administration's spending and failed to give it credit for budget cuts.

The president also said Romney's background as a millionaire private equity manager doesn't prepare him for the presidency.

"The challenge we've faced for over a decade is that harder work hasn't led to higher incomes," Obama said. "Bigger profits haven't led to better jobs. And you can't solve that problem if you can't even see that it's a problem."

The president blasted Romney's proposals for more tax cuts, again appealing to Iowa's rural sensibility: "Five trillion dollars in new tax cuts ... that is like trying to put out a prairie fire with some gasoline."

Romney aides said Obama is attacking their candidate in order to cover up his own failures.

"A president who broke his promise to cut the deficit in half by the end of his first term has no standing when it comes to fiscal responsibility," Romney spokesman Ryan Williams said.

More on Obama's Iowa appearance from Jennifer Jacobs of The Des Moines Register: