U.S. President Barack Obama defended his opposition to extending tax breaks for the country's richest citizens Wednesday, using a speech in Ohio to directly attack Republican lawmakers for wanting to "cut more taxes for millionaires and cut more rules for corporations."

Obama said the United States can't afford the US$700 billion price tag associated with keeping taxes lower for the nation's wealthiest people, a view that opposes that of House Minority Leader John Boehner and other Republican lawmakers.

In a speech at Cuyahoga Community College in Parma, Ohio, the U.S. president said the tax proposal by Republicans represents the desire to "cut more taxes for millionaires and cut more rules for corporations."

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

The massive tax cuts of the George W. Bush administration expire at the end of this year, unless Congress votes to renew them.

Obama said he believes "we ought to make the tax cuts for the middle class permanent. These families are the ones who saw their wages and incomes flatline over the last decade -- and they deserve a break. And because they are more likely to spend on basic necessities, this will strengthen the economy as a whole."

Obama's speech came as the administration attempts to jump-start a sputtering economy, including proposing a $50 billion jobs-creation package to rehabilitate the country's roads, railways and airports.

He used the opportunity to reiterate his plans to expand and extend a research and development tax credit that expired last year, and renewed calls for a small business package that has been held up by Senate Republicans.

It was also a forum to strike back at Republicans, particularly Boehner, who have criticized his stewardship of the economy.

Obama said Boehner -- who panned the administration's economic policies in a speech in the same Ohio town last month -- offered "no new ideas…just the same philosophy we already tried for the last decade, the same philosophy that led to this mess in the first place."

Earlier Wednesday, Boehner laid out his own economic proposals, suggesting Congress freeze all tax rates for two years and cut government spending to pre-2008 levels.

The debate over tax cuts and the slow economic recovery has some lawmakers wary ahead of elections this fall.

Some Democratic incumbents in conservative or swing districts have spoken out in favour of extending all tax cuts, even if temporarily, while others have said only tax cuts for the wealthy should be repealed in an attempt to appeal to middle-class voters.

In his speech, Obama acknowledged the slow pace of economic recovery, but warned against fear-mongering ahead of November's election.

"And so people are frustrated and angry and anxious about the future. I understand that. I also understand that in a political campaign, the easiest thing for the other side to do is ride this fear and anger all the way to Election Day," Obama said.

"The middle class is still treading water, while those aspiring to reach the middle class are doing everything they can to keep from drowning."

With files from The Associated Press