The 10-year outlook released by the nonpartisan Congressional Budget Office is somewhat gloomier than White House projections, which found that Obama's budget request would produce deficits that would add about $8.5 trillion to the national debt by 2020.

The CBO and the White House are in relative agreement about the short-term budget picture, with both predicting a deficit of about $1.5 trillion this year -- a post-World War II record at 10.3 percent of the overall economy -- and $1.3 trillion in 2011. But the CBO is considerably less optimistic about future years, predicting that deficits would never fall below 4 percent of the economy under Obama's policies and would begin to grow rapidly after 2015.

Deficits of that magnitude would force the Treasury to continue borrowing at prodigious rates, sending the national debt soaring to 90 percent of the economy by 2020, the CBO said. Interest payments on the debt would also skyrocket by $800 billion over the same period.

Obama's tax-cutting agenda is by far the biggest contributor to those budget gaps, the CBO said. As part of his campaign pledge to protect families making less than $250,000 a year from new taxes, the president is proposing to prevent the alternative minimum tax from expanding to ensnare millions of additional taxpayers. He also wants to make permanent a series of tax cuts enacted during the Bush administration, which are scheduled to expire at the end of this year.

"Over the next 10 years, those policies would reduce revenues and boost outlays for refundable tax credits by a total of $3.0 trillion," wrote Douglas W. Elmendorf, the CBO director. Combined with interest payments on that shortfall, the tax cuts account for the entire increase in deficits that would result from Obama's proposals.

Obama is convening a special commission to bring deficits down to 3 percent of the economy, but the CBO report shows that Obama could accomplish that goal simply by letting the Bush tax cuts expire and paying for changes to the alternative minimum tax.

Other policy changes, such as Obama's signature health-care initiative and a plan to dramatically expand the federal student loan program, would have significant effects on the budget, Elmendorf wrote, but they generally would be paid for and therefore would not drive deficits higher.