Some budget experts say even a speedy end to the war would not give Obama much money for new programs.
"You cannot justify a longer-term commitment to a program based on a one-time saving on the war in Iraq," said Stuart Butler, who studies domestic policy at the Heritage Foundation, a conservative-leaning think tank.
In addition, replenishing the military and rebuilding Iraq and Afghanistan are certain to become expensive priorities once the fighting stops, said Alice Rivlin, who directed the Office of Management and Budget for several years under Clinton.
"Savings from the Iraq war will not be all that great," she said.
Other new sources of revenue in Obama's plan include about $80 billion a year from closing tax loopholes and $100 billion from a variety of cuts in spending and revised government procurement rules.
The nonpartisan Tax Policy Center examined Obama's plans to eliminate tax loopholes and said it could not confirm the projected savings.
"If you look at official revenue estimates, the numbers come out to be less than half of what they say they're going to raise," said Len Burman, director of the center and a former Treasury official in the Clinton administration, referring to Obama's campaign staff.
McCain has cited similar proposals to free up revenue as part of his plan to balance the budget by 2013, saying he would cut pork-barrel spending and other "wasteful" programs. He says that winning the wars in Iraq and Afghanistan would generate savings that could be plowed into deficit reduction.
Unlike McCain, Obama says he could recoup about $100 billion a year by rolling back the Bush tax cuts for families earning more than $250,000 annually -- but some analysts question that too.
Those tax cuts are set to expire at the end of 2010, so repealing them a couple of years earlier would hardly result in a windfall that could be used as a continuing funding source, they say.
The Obama campaign responds that tax cuts, once enacted, are usually renewed and do not expire. Therefore, they say, Obama can legitimately claim to be recouping money for other purposes by scaling back the tax cuts.
Obama has not identified new revenue sources or spending cuts to pay for some of what he wants to do.
His $10-billion fund to reduce home foreclosures, for example, is part of a $50-billion plan to stimulate the economy through increased government spending. Paying for the program through spending cuts would defeat the point of the stimulus, the campaign says.
