WASHINGTON ― Senate Democrats on Monday unveiled a $3.5 trillion budget blueprint that proposes limited increases for defense budgets through 2031.

While non-binding, the numbers are politically symbolic, and it’s unclear whether the roughly flat top-lines for national defense will repel centrist Democrats or not, especially given the other Democratic priorities in the bill. Party leaders will need all 50 of their members to stay unified to pass the budget blueprint, focused on expanding America’s social safety net, without any Republican votes.

For the national defense budget category “050,” which includes Department of Energy weapons programs and the Pentagon budget, the blueprint proposes $765.7 billion in budget authority for fiscal 2022. The number, which includes mandatory spending, tracks with the administration’s fiscal 2022 budget request for $753 billion in discretionary defense spending, according to a Senate aide.

In the out-years, the blueprint proposes 2 percent annual increases through 2026 and then 1 percent increases per year through 2031, its final year.

That could rankle Republicans and some Democrats who have said annual increases for defense of 3 to 5 percent above inflation are needed to counter a rising China and other global threats. Some have argued that defense budget boosts that lag inflation are not flat but in fact cuts.

“The Democrats’ reckless $3.5 trillion tax-and-spend spree increases funding for everything but our national defense,” Senate Armed Services Committee Ranking Member Jim Inhofe, R-Okla., said in a statement. “That’s probably the largest ― but certainly not the only ― unacceptable part of this blueprint for more government, more taxes and higher prices. American families can’t afford this spending spree, especially because a lack of investment in national defense only puts us further behind China and Russia.”

The budget resolution, which maps $3.5 trillion in spending boosts and tax breaks aimed at strengthening social and environmental programs, sets up an autumn battle over President Joe Biden’s domestic policy ambitions.

The budget’s introduction marks the start of a long legislative trek through Congress that Democrats hope will result this fall in a progressive reshaping of government. To succeed, they’ll have to overcome likely unanimous Republican opposition and find the sweet spot between the demands of their own often antagonist progressive and moderate factions.

That will be a fraught task in a Congress they control by a hair. They’ll need the support of every Democrat in the 50-50 Senate, with Vice President Kamala Harris casting the tie-breaking vote, and will be able to lose only three Democrats in the House — margins that give each Democrat leverage.

“At its core, this legislation is about restoring the middle class in the 21st Century and giving more Americans the opportunity to get there,” Senate Majority Leader Chuck Schumer, D-N.Y., said in a letter to his colleagues unveiling the plan.

To pass the annual defense authorization bill, lead Democrats have acknowledged in recent weeks that winning support from Republicans ― and some Democrats ― will mean boosting the top-line above Biden’s proposal. Because passing the budget blueprint is expected to be a partisan affair that relies on Democratic unity, the calculation is likely a different one, and how the defense numbers will factor in isn’t immediately clear.

The budget resolution assigns congressional committees specific amounts of money to spend and describes policy changes party leaders support. A follow-up bill would actually enact those changes.

But those committees will have final say on the legislation they produce, and crafting this fall’s Democratic compromise with virtually no margin of error will be a time-consuming challenge for party leaders.

The resolution’s defense numbers are problematic politically, according to Mackenzie Eaglen, a defense budget analyst with the conservative American Enterprise Institute.

“In Congress, there are more votes to increase the defense budget than to cut it,” Eaglen said. “Budget resolutions often don’t survive contact with reality, and this one is no different. With inflation at potentially 5 percent or higher next year, the budget resolution would have consequences for nearly every defense community — in red and blue states equally.”

As a practical matter, the proposed numbers beyond 2022 are unlikely to stick and will be revised again next year, said Todd Harrison, of the Center for Strategic and International Studies.

“A budget resolution isn’t a law, it’s just a set of guidelines Congress uses to direct the efforts of the appropriators,” Harrison said, adding that the “FY22 numbers would be would ‘binding’ on [Senate defense appropriators], unless Congress comes back and makes an exception ― but the numbers for FY23 and beyond are really just there for the purpose of deficit projections.”

Democrats are expected to approve the resolution over unanimous Republican opposition, perhaps as soon as this week. Passage of the budget resolution is crucial because it would allow a subsequent bill — actually enacting Democrats’ 10-year, $3.5 trillion plan for spending and tax changes — to pass the Senate by a simple majority.

Without that protection, the follow-up measure would fall prey to a GOP filibuster, delaying tactics that require 60 votes to end.

With reporting by the Associated Press.

Joe Gould is senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry.

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