Making a decidedly low-key maiden trip to Iowa on Friday, Mitt Romney delivered a sharp critique of President Obama, saying his presidency was “an experiment” that had “failed because he doesn’t understand how the economy works.”

Romney, the presumptive front-runner for the 2012 Republican presidential nomination, gave a speech here focused squarely on the economy and job creation. But as he embarked on his first trip of the year to Iowa, a state most of his rivals have visited many times already, the former Massachusetts governor left open the question of how seriously he will compete in the state’s first-in-the-nation caucuses.

In a 20-minute address, Romney did not mention any other GOP candidate, instead drawing a contrast between his record as a businessman and single-term governor and Obama’s record in the White House. He said voters in 2008 picked Obama “as an experiment” and he likened Obama’s policies to those adopted by European nations, warning that they could result in a lower standard of living and “structural long-term unemployment.”

“With the economy going down, with tumult in the world, we picked a fine time to pick as our president someone with no experience in the private sector, no experience in the economy, no experience in negotiations, no real experience in leadership,” Romney said. “You see, to create jobs, it helps to have actually had a job.”

Romney added that businesses are hurting because of “uncertainty” that the Obama administration has created about government regulations and taxes. “I spent my life in the private sector,” Romney said. “I know that business and entrepreneurs and innovators and employers can handle bad news. They have to, because it happens now and then. What we have a hard time handling is uncertainty.”

And Romney said the government was borrowing too much money, “year after year after year,” with no capacity to pay it back. “In business, you’ll go out of business. You’ll go bankrupt,” he said. “But in government, you can sort of kick the can down the road for a long, long time. Ultimately, however, the piper has to be paid.”

Romney’s visit came as Iowans openly wonder whether he would compete as aggressively in the caucuses here as he did in the 2008 race. He is planning to officially announce his candidacy in New Hampshire next week.

As he grabbed the microphone on stage here, Romney looked out at the Iowans sitting on folding chairs and remarked: “I see so many friends here. It’s great to see you again. It’s good to be home. This isn’t exactly home, but it felt like it the last time I was around, so I want to thank you for welcoming me like an old member of the family.”

But an hour earlier, he told reporters he had not decided whether to participate in this summer’s Ames Straw Poll, an important event on the Iowa calendar.

“As to the tactics of a campaign and where you devote your financial resources and your time resources, that’s something we’ll figure out as we go along,” Romney told reporters at a campaign stop in nearby Ankeny. “You’ll see everybody who’s intent on sitting in the White House coming to Iowa and spending time here, debating here, and just how we do that will probably be defined by different candidates in different ways.”

Romney, in Levis, loafers and an open-collar shirt, stopped by AgVision, an agriculture software firm, to talk about the economy. He has made visits to small businesses a centerpiece of his campaign.

Romney declined to say whether, if he were president, he would sign into law the GOP Medicare plan authored by House Budget Committee Chairman Paul Ryan (R-Wis.) — something that a rival, former Minnesota governor Tim Pawlenty, said Thursday he would do.

“That’s the kind of speculation that is getting the cart ahead of the horse,” Romney told reporters. “I’m going to propose my own plan, and my plan will be somewhat different than what the Paul Ryan plan is, but I support the objectives of the Paul Ryan plan, which is keeping Medicare alive, keeping it solvent and keeping the nation solvent.”

After his speech in Des Moines, Romney held a question-and-answer session. But it was interrupted by the building’s fire alarm, which was triggered by a burning bag of microwave popcorn.

“Uh oh, they want to get us out of here, don’t they?” Romney said over the sound of the alarm. “I wasn’t trying to get out of tough questions — I promise.”

He then took another question.

“Do you really think you can win Iowa given the strength of social conservatives in this state?”

“Do I think I can win Iowa?” Romney responded. “Can I win Iowa?”

The audience clapped. Some shouted “yes!” And then Romney told everyone to quickly evacuate the building.

With that, Romney climbed into his sport-utility vehicle. He was off to Cedar Rapids for a picnic, where he was sure to see more familiar Iowans.