导读：美国总统奥巴马承诺，九月份国会召开时，将提出改善美国经济萎靡不振的计划。如何改善美国的失业状况对于2012年总统大选的投票者们来讲，是一个很重要的问题。奥巴马在周一晚上爱荷华州迪科拉市回答提问时表示将在九月份推出新计划，刺激美国经济，增加就业机会并控制财政赤字。但奥巴马此举有被认为是为2012总统大选造势，他强调刺激经济和医疗改革旨在赢在总统连任。前明尼苏达州州长Tim Pawlenty 宣布推出大选，而罗姆尼 (Romney), 巴克曼女士(Bachmann) 和 得克萨斯州州长里克·佩里将参选竞争。
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.
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.
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."
Ina 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.
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.