Discretionary spending, though, is expected to decline over the decade as a share of the economy. Military spending — which Republicans have thus far refused to reduce as part of talks with Mr. Biden’s team — should tick down slightly from 3 percent of the economy. Discretionary spending outside the military is now 3.6 percent but is expected to fall to 3.2 percent by 2033.
Social Security and Medicare, conversely, are expected to grow rapidly over the next 10 years, as retiring baby boomers qualify to receive health and retirement benefits. Social Security spending will rise from 4.8 percent to 6 percent of the economy in that time, the budget office projects, and Medicare will rise from 3.9 percent to 5.3 percent.
Analysts say those programs are the primary reason budget forecasts have long shown federal spending increasing in the coming decades — even before Mr. Biden took office.
“The entirety of the overall federal spending increase relative to G.D.P. over the long term can be accounted for by the growth in the major federal health programs (Medicare, Medicaid, and the A.C.A.) and Social Security,” Charles P. Blahous, who studies federal spending and debt at the Mercatus Center at George Mason University, told the Senate Budget Committee this month in written testimony.
Conservative groups have criticized Republicans for not including the safety-net programs in debt demands. “While current debt ceiling negotiations largely concern ways to restrain the discretionary parts of the budget, any serious proposal to tackle the emerging debt and deficit crisis must also address our largest mandatory spending programs: Social Security and Medicare,” Alex Durante, an economist at the Tax Foundation, which promotes lower taxes, wrote on Wednesday.
Liberal groups and the White House have criticized Mr. McCarthy and his team for neglecting the other side of the fiscal ledger: the nation’s tax system. Tax receipts briefly surged last year but are expected to fall back toward historical norms this year, stabilizing around 18 percent of the economy, the budget office projects. Mr. McCarthy has cited last year’s numbers to incorrectly claim current tax revenues are near record highs.