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

美国总统奥巴马承诺在下个月拿出一项“非常具体”的刺激经济计划。

In Iowa on day one of a rural Midwest bus tour, he said he would put forward the blueprint¹ when Congress returned in September.

As President Obama spoke², 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 deficit³.

"And my attitude is - get it done."

'Lowering the rhetoric⁴'

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

The tour - in an imposing⁵ 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, indirectly⁶, 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 negotiations⁷ to terrorists.

Mr Obama replied: "In fairness, since I have been called a socialist⁸ 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（修辞） ."

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.