"For the president of the United States to stand up and say the private sector is doing fine is going to go down in history as an extraordinary miscalculation," Romney told the crowd.
Romney also addressed the president's argument that the federal government should help state and local jurisdictions hire more employees, citing the recent recall election in Wisconsin. Gov. Scott Walker was able to fend of a challenge there inspired by his move to block state workers from collectively bargaining.
"Did he not get the message of Wisconsin? The American people did. It's time to cut back on government," Romney said.
The Obama campaign defended the president's comments Friday during a call with reporters.
"The fact is that businesses have now created more than 4.3 million private sector jobs, manufacturing is resurgent," said Obama spokesman Ben LaBolt, who said Obama "took office in the midst of a severe economic crisis and fought back against that."
But Republicans nevertheless sense opportunity, and Romney repeatedly hammered the comment on the stump.
"I think he's defining what it means to be detached and out of touch with the American people," Romney said.
The attacks dovetailed into Romney's standard stump speech, which normally attacks the president over his economic policies. But there was a notable new addition to Romney's standard cannon of stories — a mention of campaigning with Sen. Marco Rubio (R-Fla.), considered to be among the finalists for Romney's vice presidential nomination.
Mention of Rubio's name elicited loud cheers from the crowd of around 400 Iowans.
Earlier in the day, Romney hosted a roundtable with farmers and small-business owners in Iowa, considered by both campaigns to be among the most crucial swing states in November's election.