Media playback is unsupported on your device Media caption President Barack Obama: ''It's time to put country first''

US President Barack Obama has promised a "very specific" plan next month to improve the flagging US economy.

In Iowa on day one of a rural Midwest bus tour, he said he would put forward the blueprint when Congress returned in September.

As President Obama spoke, his would-be 2012 Republican challengers blamed him for the flagging American economy.

With US unemployment jammed at just above 9%, jobs could well remain a major issue for voters in 2012.

Responding to a question in a town hall in Decorah, Iowa, on Monday evening, Mr Obama said: "I'll be putting forward when they [lawmakers] come back in September a very specific plan to boost the economy, to create jobs and to control our deficit.

"And my attitude is - get it done."

'Lowering the rhetoric'

Mr Obama set off on Monday morning on a three-day swing through Minnesota, Iowa and Illinois.

Image copyright AP Image caption President Obama clashed with a member of the Tea Party in Iowa

The tour - in an imposing Secret Service armoured bus - is officially a White House event, although Republicans called it a campaign trip.

The BBC's Marcus George in Washington says Mr Obama is trying to reassert his leadership and, indirectly, shore up support in states that could make or break his campaign for a second term.

During Mr Obama's stop in Decorah, he clashed with a local leader of the conservative Tea Party, Ryan Rhodes.

Mr Rhodes referred to reports that Vice-President Joe Biden had likened Tea Party members during recent debt-ceiling negotiations to terrorists.

Mr Obama replied: "In fairness, since I have been called a socialist who wasn't born in this country, who is destroying America and taking away its freedoms because I passed a health care bill, I am all for lowering the rhetoric."

Mr Obama's approval rating dipped below 40% for the first time in a Gallup daily tracking poll on Sunday, although recent polls have shown far lower voter satisfaction with Congress.

'Magical Misery bus tour'

Analysts say Mr Obama's challenge is to convince voters that his policies - including a $787bn (£482bn) economic stimulus package and health care reforms - have helped the economy, not hindered it.

Image copyright Reuters Image caption Republican candidate Rick Perry is a "good-looking rascal", according to Bill Clinton

Presumptive Republican frontrunner Mitt Romney labelled Mr Obama's trip the "Magical Misery bus tour".

The former Massachusetts governor said in a statement the president was "more interested in campaigning in swing states than working to solve the economic crisis crushing the middle class".

Texas Governor Rick Perry meanwhile completed his first full day of campaigning, telling the Associated Press news agency: "I respect all the other candidates in the field but there is no one that can stand toe-to-toe with us."

In an interview with an Iowa newspaper, Mr Perry also challenged Mr Obama, to "get rid of the regulations stifling jobs in America".

Mr Perry received an unexpected compliment in New York on Monday from Democratic former President Bill Clinton.

Mr Clinton said the Texan was a "good-looking rascal," but indicated he was not so impressed by Mr Perry's policies.

Republican congresswoman Michele Bachmann will begin a bus tour on Tuesday in South Carolina, buoyed by her win in Saturday's non-binding "straw poll" in Iowa.

Former Minnesota Governor Tim Pawlenty dropped out of the race after finishing a distant third in that poll. Mr Romney did not compete.

Mr Romney, Ms Bachmann and Mr Perry are each vying to become the Republican nominee and challenge Mr Obama for the White House in 2012's elections.

With the first real voting not scheduled to take place until February, correspondents say plenty of time remains for more upheaval in the Republican race.

This could include a late entrance from Sarah Palin, the former Alaska governor, 2008 vice-presidential nominee and conservative Tea Party hero.