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House Democrats on Thursday unveiled details of an $825 billion plan designed to boost the sagging U.S. economy.

The package is a mixture of $550 billion in spending programs and $275 billion in temporary tax cuts that Democrats hope will add 3 to 4 million jobs to the American workforce.

"We wanted to get the biggest bang for the buck of every dollar spent," said House Speaker Nancy Pelosi, D-Calif.

At $825 billion, the legislation would be one of the largest bills ever to move through Congress, and by traditional standards, lawmakers were moving with unusual speed. Pelosi and Sen. Harry Reid, D-Nev., the Senate Majority Leader, have pledged to have it ready for Obama's signature by mid-February.

The primary author of the legislation, House Appropriations Committee Chairman David Obey, D-Wis., described the package as "the largest effort by any legislative body on the planet ... to prevent an economic catastrophe."

Republicans, usually quick to lambaste Democrats for massive spending proposals, were initially muted in their criticism of the measure.

"We want to scrub this bill," said Rep. Paul Ryan, R-Wis., the top Republican on the House Budget Committee. "We want to keep an open mind."

Republicans are carefully weighing the proposal. One senior Republican indicated that even though the bill contains a lot of spending, colleagues could find the tax breaks particularly appealing.

While some Republicans were careful not to take a confrontational tone with Democrats on the issue, House Minority Leader John Boehner, R-Ohio, did not hold back.

"Oh my God!" Boehner exclaimed as he reacted to the size of the proposed program.

"My notes here say that I'm supposed to say I'm disappointed. I can't believe what I'm seeing," he said. Boehner also noted that Democrats prepared the legislation "with no Republican input at all."

But Boehner's top lieutenant, House Minority Whip Eric Cantor, R-Va., said that President-elect Barack Obama has indicated he wants input from Republicans on this bill.

"This is exactly where we can play a role. Clearly we are on that page with the President-elect," he said.

Democrats must also persuade moderates in their own caucus to support the bill.

"If you're going to put a stimulus out there, there's no way you'll find all of the pay-fors," said Rep. Charlie Melancon, D-La., one of the leaders of the so-called Blue Dog Democrats, a group of fiscally conservative lawmakers who expect spending programs and tax cuts to be paid for.  "And if you find the pay-fors, you negate the stimuli."

Three House committees plan to begin writing final versions of the legislation next week with a floor debate coming the week of Jan. 25.

The measure calls for $87 billion to help the states meet the rising cost of providing health care for the poor in the recession, and another $39 billion to subsidize coverage by out-of-work wage-earners who cannot afford the cost of their employer-covered health care.

More than $100 billion is ticketed for education, including money for school districts to shield them from the effects of state cutbacks in services. Democrats also provided tens of billions in spending and tax breaks designed to lessen the nation's dependence on oil as a principal source of energy.

Obama's top aides have worked closely in recent days with Democrats in Congress to shape legislation that generally adheres to the president-elect's wishes.

At the same time, lawmakers departed dramatically in one area, jettisoning the incoming administration's call to give a $3,000 tax credit for each new job created by private companies.

Another key priority of the new administration was preserved, though. The summary calls for a tax credit of $500 per worker and $1,000 per working couple.

The measure does not include money to help middle- to upper-income taxpayers ensnared in the alternative minimum tax, which was originally designed to prevent the extremely wealthy from avoiding payment of taxes but now threatens more than 20 million tax filers. Several officials said the Senate was likely to include that provision in its version of the bill, a step that could push the overall total close to $900 billion.

With unemployment rising, and applications for various forms of federal aid keeping pace, the legislation calls for increased spending on food stamps, unemployment insurance and job training. It also proposes an increase in Pell Grants for college students of $500.

House leaders called for $30 billion for highway construction and $10 billion for mass transit and rail.

The summary claimed "unprecedented accountability" and said the bill would include no earmarks, the pet projects that lawmakers are fond of.

In addition, Democrats said all announcements of contract and grant competition would be posted on a Web Site to be created by the new administration.

Included is $32 billion to upgrade the nation's electrical distribution system, more than $20 billion in tax cuts to promote the development of alternatives to oil fuels, and billions more to make public housing, federal buildings and modest-income homes more energy efficient.

Across the Capitol, a companion measure is expected to move along roughly the same timeline in the Senate, and congressional leaders have expressed confidence they would be able to agree on a final version by the time of a scheduled vacation coinciding with Presidents' Day.

Other items in the measure include funds for state and local law enforcement funds, extending broadband service to rural and other underserved areas, and money to computerize health records, a key priority of the incoming president.

Businesses would be able to reduce their taxes through a provision that expands their ability to write off current losses again past profits, and by accelerating the depreciation of new plants and equipment.

First-time homeowners also would get a break. The bill eliminates the requirement for them to repay a new $7,500 tax credit created in a housing measure that passed last summer.

FOX News' Chad Pergram and The Associated Press contributed to this report.