One of the biggest reasons the Trump budget fell short is that the budget office did not agree that its proposals would generate as much economic growth as the White House has suggested. It said that the average gross domestic product growth over 10 years is currently 1.8, and that under Mr. Trump’s plan it would be 1.9 percent — far lower than the 3 percent the administration assumes.

The lack of specifics in Mr. Trump’s plans was also a problem for the Congressional Budget Office. It said that in many cases where Mr. Trump’s policy initiatives lacked details, its analysts had to use place-holder figures.

The $4.1 trillion budget for 2018 that the White House proposed recommended a large increase in spending on the military and on border security. By assuming rapidly accelerating economic growth, Mr. Trump’s economic team was able to make the budget balance without making changes to Social Security’s retirement program or Medicare, the two biggest drivers of America’s federal government debt.

Tepid economic growth and an aging population have raised concerns about the future of those programs. The Trump administration said Thursday that the financial outlook for Medicare’s Hospital Insurance Trust Fund had slightly improved in the last year but that Social Security still faced serious long-term financial problems.

The Medicare trust fund will be depleted in 2029, the administration said. Last year the government said that the trust fund would be exhausted in 2028.