WASHINGTON (AP) -- Facing Republican resistance to a massive economic stimulus plan, the Obama administration on Wednesday said $3 of every $4 in the package should be spent within 18 months to have maximum impact on jobs and taxpayers.

Peter Orszag, the director of the White House Office of Management and Budget, said Wednesday that if House or Senate versions of the bill do not spend the money as quickly, the White House will work with lawmakers to achieve the 75 percent goal. Congress is working on a stimulus bill of at least $825 billion.

In an interview with the Associated Press, Orszag responded to a Congressional Budget Office assessment that money targeted for infrastructure under a House proposal would take years to be spent. He said the issues identified by CBO could be easily corrected.

"There are relatively straightforward changes to increase the spend-out on that part of the bill," Orszag said.

CBO concluded that only $26 billion out of $358 billion in infrastructure and other appropriated spending would be delivered into the economy by the Sept. 30 end of the budget year. The CBO's analysis applied only to 40 percent of the overall stimulus bill. Still, Republicans cited the study in pushing for more tax cuts and less spending

Indeed Republicans, who said they were receptive to Obama's call for a "unity of purpose," promptly tested the day-old administration. They criticized the Democratic plan and requested a meeting with the president to air their tax-cutting plans.

Congressional officials said a meeting was planned for next week.

The maneuvers illustrated Obama's governing predicament: He wants to move swiftly to confront the troubled economy while also living up to a vow to break through the traditional partisan barriers.

Obama met with his top White House economic advisers Wednesday afternoon, including Orzag, National Economic Director Lawrence Summers, White House Policy Council Director Melody Barnes and White House coordinator of energy and climate policy Carol Browner.

A senior administration official said the group discussed the status of the markets, the stimulus package and a financial industry bailout. The official spoke on condition of anonymity because the meeting was private.

While pledging to use the money swiftly, Orszag in the interview defended the need for some spending outside the 18 month window to avoid a sudden end to the government's infusion.

"There is an important economic argument that you don't want to jump-start the economy and then create a huge air pocket at the end," he said.

Meanwhile, the chairman of the House Appropriations Committee voiced doubts about whether the package was big enough to slow or redirect the economy's downward path.

"This package is no silver bullet," the chairman, David Obey, D-Wis., cautioned. "What it is aimed at is staving off the worst aspects of this recession. ... I don't know, frankly, if it will be adequate."

Timothy Geithner, Obama's nominee for secretary of the treasury, told senators the country needs a "forceful course" to meet the economic crisis.

"The ultimate costs of this crisis will be greater if we do not act with sufficient strength now," Geithner told the Senate Finance Committee. "In a crisis of this magnitude, the most prudent course is the most forceful course."

Congressional Republicans, meanwhile, insisted the package needed to be tilted more toward tax cuts.

"The challenge as we see it is to create a plan that helps middle-class taxpayers and small businesses without wasting money or exploding our national deficit," House GOP leaders wrote in a letter to the White House.

The House Appropriations Committee on Wednesday night approved by 35-22 party-line vote spending a $358 billion portion of the stimulus measure.

The sweeping plan blends traditional public works programs such as road and bridge construction and water and sewer projects with new ideas such as upgrading the nation's electricity grid and investments in health care information technology systems.

The measure contains temporary spending increases for dozens of programs across the federal government. There's money to weatherize poor people's homes, boost spending for community health centers, relieve a backlog of construction projects at national parks and purchase buses for local mass transit agencies, just for starters.

"That's a hell of a lot of money," Rep. Rodney Frelinghuysen, R-N.J., said of a $6 billion weatherization program, a 30-fold increase.

In a day when economic developments moved on several fronts, the House voted 260-166 to impose new goals and tougher restrictions on the $700 billion financial bailout fund. Half of the money from the Troubled Asset Relief Program has already been committed by the Bush administration, but Obama got permission from the Senate last week to tap the remainder.

The House legislation would devote $40 billion to $100 billion of the financ