CLEVELAND -- Politically weakened but refusing to bend, President Barack Obama insisted Wednesday that Bush-era tax cuts be cut off for the wealthiest Americans, joining battle with Republicans, and some fellow Democrats, just two months before bruising midterm elections.

Singling out House GOP leader John Boehner in his home state, Obama delivered a searing attack on Republicans for advocating "the same philosophy that led to this mess in the first place -- cut more taxes for millionaires and cut more rules for corporations."

Obama rolled out three new plans to help spur job growth and invigorate the sluggish national economic recovery.

They would expand and permanently extend a research and development tax credit that lapsed in 2009, allow businesses to write off 100 percent of their investments in equipment and plants through 2011 and pump $50 billion into highway, rail, airport and other infrastructure projects.

The package was assembled by the president's economic team after it became clear that the recovery was running out of steam.

There was a political component too. With Democrats in danger of losing control of the House in November, Obama is under heavy pressure to show voters that he and his party are ready to do more to get the economy moving and get millions of jobless Americans back to work.

However, none of Wednesday's proposals, nor Obama's call for allowing tax rates to rise for the wealthiest Americans, seems likely to be acted on by Congress before the elections, reflecting the battering Obama and congressional Democrats have taken in public opinion polls.

Obama made one of his strongest appeals yet to allow the tax cuts passed under President George W. Bush, in 2001 and 2003, to expire at the end of the year on schedule, but just for individuals earning more than $200,000 annually or joint filers earning over $250,000.

The changes would affect dividend and capital-gains rates and various other tax benefits as well as income from wages and salaries.

The president's strategy of pushing for legislation to save some tax cuts but not all carries its own risks.

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Because all the tax breaks would expire automatically at the end of the year if Congress failed to act, that could result in sweeping increases for taxpayers at every income level, a major blow to recovery hopes and a colossal dose of blame for voters to parcel out to lawmakers and the White House.

Some influential Democrats, and Obama's own former budget director, Peter Orszag, have suggested a compromise might be necessary, one to temporarily extend all the tax cuts, perhaps for a year or two.

But in his remarks in Cleveland, Obama strongly signaled that he wasn't about to sign off on any such deal.

"Let me be clear to Mr. Boehner and everyone else. We should not hold middle class tax cuts hostage any longer," the president said. The administration "is ready this week to give tax cuts to every American making $250,000 or less."

It was a slight misstatement of his own position, since the $250,000 would apply to household income. The threshold for individuals would be $200,000

The White House said Cleveland was picked as the speech site because Boehner laid out his party's economic agenda here in an Aug. 24 speech.