The United States is on a pace to add nearly $19 trillion to its national debt over the next decade as the mounting costs of an aging population and higher interest expenses continue to weigh on the nation’s fiscal outlook, the nonpartisan Congressional Budget Office said on Wednesday.

But the report did offer a sliver of relief: Recently enacted legislation to curb federal spending and a U.S. economy that has been growing faster than expected are making the fiscal picture slightly less bleak. Annual deficits over the next decade are 7 percent smaller than the $20.3 trillion the budget office forecast last year.

That decline reflects several conflicting forces. A deal that President Biden and congressional Republicans struck last year to limit discretionary spending for two years reduces deficits over the decade. So does a surge of 5.2 million new workers into the labor force, most of them immigrants.

But those deficit declines are partly offset by an increase in the estimated budget costs from Mr. Biden’s clean-energy agenda, an aging U.S. population and higher interest rates on the national debt.

In a statement released with the report, the budget office’s director, Phillip L. Swagel, said that even with the decline in deficits, the nation remained on track to rack up more debt as a share of its total economic output in 2034 than at any other time in its history.

The projections for the nation’s finances come as Congress faces another deadline next month to agree on federal spending legislation to keep the government running. Lawmakers are also engaged in a heated debate over providing more aid to Ukraine and Israel and whether to expand the child tax credit and restore expired business tax breaks.