President Barack Obama’s budget would produce $2.3 trillion more in deficits over the next decade than the administration projects, according to the Congressional Budget Office.

The nonpartisan agency said today the administration’s plan would generate $9.5 trillion in deficits between 2012 and 2021, compared with the $7.2 trillion forecast last month by the White House budget office.

The difference is partly attributable to the CBO’s more conservative estimates of how quickly the U.S. economy will grow in coming years, which results in less tax revenue pouring into the Treasury.

The CBO also said that deficits under the plan wouldn’t shrink to less than 4.1 percent of the nation’s gross domestic product, a level economists generally consider to be unsustainably large. The administration projected deficits would shrink to as little as 2.9 percent of GDP.

The annual report is designed to provide lawmakers with an independent assessment of the president’s budget request.