DECORAH, Iowa – President Obama ditched Washington on Monday to begin a three-day Midwest bus trip that had the air of a campaign tour, with cheering crowds, stops for pie, pictures with smiling children and barbs at Republicans — including his prospective 2012 opponents.

The trip came as polls find the American public increasingly worried about the stalled economy and weak job market. But Obama said the biggest stumbling block to recovery is partisanship in Washington.

“You’ve got to send a message to Washington that it’s time for the games to stop,” he told a crowd here and at his first stop in Cannon Falls, Minn.

“With the markets going up and down last week and this (U.S. credit rating) downgrade, a lot of folks were feeling a little anxious and distressed,” Obama said. “Some folks worried that we might be slipping back. I want all of you to understand that there is nothing that we’re facing that we can’t solve with some spirit of America first, a willingness to say we’re going to choose country over party.

“There is no shortage of ideas to put people to work right now. What is needed is action on the part of Congress,” he said.

In tiny Decorah, Iowa, where he stood before an iconic red barn, his stage flanked with hay bales, Obama was pressed to defend his compromises on the debt-ceiling fight and health care by a largely supportive crowd. One woman said she was a “big supporter,” but asked him what prevented him “from taking a harder negotiating stance” with Republicans.

“Sometimes you’ve got to make choices to do what’s best for the country,” Obama said. “That’s what I tried to do.”

The tour of small towns in three Midwestern states that Obama carried in 2008, and needs to win in 2012, comes as the Republican field of challengers is taking shape and signals the start of the presidential campaign. Though the White House said the trip was official business — the president will announce new jobs initiatives today at a White House Rural Economic Forum in Iowa — Obama brought up his potential rivals at both stops.

The trip comes just before he leaves Washington for a 10-day vacation, and as a recent Gallup poll found him with the lowest approval ratings since he took office in 2009 — hovering at 39 percent.

Earlier, in Cannon Falls, Obama mentioned the Republican presidential candidates’ debate last Thursday night, in which all 10 GOP presidential hopefuls turned thumbs down to a hypothetical deal to tame the deficit that would be weighted 10-to-1 in favor of spending cuts to tax hikes.

“That’s just not common sense,” the president said.

He was in exceedingly friendly territory fielding questions at the outdoor Minnesota town hall, which had the festive air of a Fourth of July cookout, including a massive American flag flanking the stage.

Katrina Karlsen Carlson, 51, who lost her job last October and has yet to find a new one, scored a picnic table just two seats away from the presidential lectern. She doesn’t blame Obama for her poor job prospects.

“That our boat is still afloat, he deserves so much credit,” Karlsen Carlson said. “It was like the Titanic when he took office and we didn’t sink.”

Karlsen Carlson voted for Obama in 2008, and will do so again, she said.

“We need to think for ourselves,” she said. “These Republicans would have us believe this economy is of Obama’s making.”

Along the bus route, however, some Minnesotans displayed cooler feelings: “Obama take your BS and go home,” read a sign posted on a giant steer on a bluff along the highway.