March 20 (Bloomberg) -- President Barack Obama’s budget will generate bigger deficits than advertised every year for the next decade, including a $1.85 trillion shortfall this year, according to a new report.

The nonpartisan Congressional Budget Office said today the deficit for the fiscal year ending Sept. 30 will be $100 billion larger than what the administration projected. CBO estimated next year’s deficit will reach $1.38 trillion, about $200 billion more than the White House projected.

Between 2010 and 2019, CBO said, the government’s deficits will total $9.27 trillion, about $2.3 trillion more than the administration forecast.

As a share of the economy, CBO said, the deficit would total 13 percent this year, 10 percent next year and remain above 4 percent through 2019. The agency said government debt will eventually double to 82 percent of the nation’s gross domestic product by 2019 from 41 percent last year.

The CBO figures will likely make it harder for Obama to gain approval of major items on his legislative agenda, including plans to expand health-care coverage and rein in greenhouse gas emissions.

The CBO, Congress’s official scorekeeper, published today its assessment of how Obama’s budget request, released last month, would affect the government’s checkbook.

‘Wake-up Call’

“This report should serve as the wake-up call this administration needs,” said House Minority Leader John Boehner, an Ohio Republican. “We simple cannot continue to mortgage our children and grandchildren’s future to pay for bigger and more costly government.”

Senate Budget Committee Chairman Kent Conrad, a North Dakota Democrat, said “the reality is that we are going to have to make adjustments to the president’s budget if we want to keep the deficit on a downward trajectory.” He also said that “despite these new numbers, we will adopt a budget resolution that reflects the key priorities of the president and the nation.”

White House Budget Director Peter Orszag emphasized that long-range budget projections are inherently uncertain because they rely on scores of assumptions about how the economy will perform over several years.

‘Technical Assumptions’

“There are huge numbers of technical assumptions that go into these overall calculations that for technical reasons can, and historically have, varied between different organizations,” Orszag said in a conference call with reporters.

Orszag also said he expected lawmakers to make some changes to the administration’s budget. “It’s not the like the process would normally just have them take the budget, Xerox it and vote on it,” he said.

White House Spokesman Robert Gibbs said “the president remains confident that we can pass the budget that he sent up, making the critical investments that we need.”

The gloomier numbers are largely attributable to expectations by the CBO that the economy won’t grow as quickly as the White House predicts. Slower economic growth means less tax revenue pouring into the Treasury.

The agency said it expects the economy to contract this year by 3 percent before growing again in 2010 by 2.9 percent. Obama’s budget assumes the economy will shrink this year by 1.2 percent before growing next year by 3.2 percent.

Unemployment Projections

The CBO said the nation’s unemployment rate will increase to 9.4 percent by the end of this year before declining to 8.5 percent by the end of 2010. Last month, the unemployment rate jumped to 8.1 percent, the highest level in more than a quarter century.

The estimate comes as lawmakers prepare their budget plans for the 2010 fiscal year, which begins Oct. 1. The House Budget Committee is slated to consider its tax-and-spending plan March 25, with floor action likely the following week. Lawmakers will use the CBO’s numbers for their budget blueprint.

To contact the reporter on this story: Brian Faler in Washington at bfaler@bloomberg.net.

Last Updated: March 20, 2009 17:04 EDT