Senate Republicans are preparing to depart Washington at the end of the week without approving President Donald Trump’s request for $350 billion in defense funds, leaving the Pentagon to confront how much of its ambitious spending plan can fit into the regular budget.

Lawmakers, Deputy Defense Secretary Steve Feinberg and other senior Pentagon officials held multiple closed-door meetings over the past two weeks about the department’s overall $1.5 trillion budget plan. But Republicans remain divided over how to finance the buildup, and there is no immediate path for the reconciliation package before the recess, which ends Nov. 9.

The administration has split its defense ambitions among three funding tracks: a regular budget of roughly $1.15 trillion, roughly $350 billion through the Republican-only reconciliation process and a separate $67 billion supplemental spending request to cover unbudgeted costs from the Iran war. Trump said in his address to the United Nations last week that he wants a total defense budget of $1.5 trillion.

Senate defense hawks are on board. But deficit-minded Republicans are unwilling to add hundreds of billions of dollars in defense spending without cuts elsewhere to offset them. Democrats — who usually supply at least some votes for national security spending — are reluctant to help fund an Iran war that polls show is unpopular with voters.

Sen. Roger Wicker (R-Mississippi), the Senate Armed Services Committee chair, said he believed there was still time for the Senate to craft its own package before the recess begins this week. But Sen. Ron Johnson (R-Wisconsin), whose support as Senate Budget Committee chair would be crucial to moving a Republican-only package, said he had no plans to do so until after November’s midterm elections. Johnson said Feinberg and other Pentagon officials he met with this month made a compelling case for the added spending, but the offsets he would need have not been identified.

“We have to satisfy the deficit hawks like we satisfy the defense hawks,” he said. Asked what that would require, he said, “Pay for it.”Senate defense hawks are pushing for a reconciliation package that exceeds $300 billion and includes the president’s Golden Dome missile defense shield, munitions replenishment and production-line expansion, and at least some portion of the administration’s supplemental request.

“We have to just make the case to every single Republican and as many Democrats as will listen, and even if it comes down to a 50-senator vote, we need to socialize and keep pushing the importance of this,” said Sen. Kevin Cramer (R-North Dakota), a member of the Senate Armed Services Committee. “Defending the country is the most legitimate, and in some respects, the only legitimate thing the federal government does.”

Cramer, whose state is expected to play a role in Golden Dome, panned the House-passed reconciliation instructions, which set aside only $60 billion for the Pentagon. He wants the Pentagon to get the entire $350 billion.

Identifying $350 billion in cuts to offset that spending would be a daunting task, both politically and budgetarily. The figure amounts to one-fifth of discretionary spending proposed for 2027, while much of the rest of the federal budget is tied up in mandatory programs such as Social Security and Medicare, or interest on the debt.

Pentagon officials have already been mulling what happens if Congress does not provide all of the defense plus-up through reconciliation. Pentagon Comptroller Jay Hurst said this month that Congress was working to incorporate some Pentagon priorities into the discretionary spending bill if the administration does not get everything it wants through reconciliation. He specifically pointed to the munitions investments Feinberg has championed.

If approved, that spending would underpin the administration’s push to sharply expand weapons production, including a long-term production ramp-up for missile interceptors, Tomahawk missiles and more. The Pentagon has reached several framework agreements with weapons makers, but they depend on Congress providing the money.

Moving those priorities into the regular budget wouldn’t necessarily solve the Pentagon’s problem. The appropriations process is also stalled. Congress is funding the government at current levels through Dec. 11, leaving major decisions for the lame-duck session, when lawmakers return after the midterms with a clearer sense of each party’s leverage heading into the next Congress.

“Last year we got 11 and a half of the [appropriations] bills done, and I hope that we could get them all done, but you never know,” said Sen. Susan Collins (R-Maine), the Senate Appropriations Committee chair. “That depends on whether the Democrats are going to cooperate.”Even before Congress resolves those larger funding questions, the Pentagon is already reshuffling money among existing accounts to cover immediate operational demands, including costs associated with the Iran war.

The department has deferred maintenance and some training to manage shortfalls while facing higher-than-expected personnel costs — and the Navy has said it is $6 billion to $8 billion short just to cover Iran war costs.

The Pentagon has asked Congress to let it shift $4.3 billion in existing funds, including $3.76 billion for higher-than-expected personnel costs, drawing money from shipbuilding, aircraft procurement and research and development.

“Their options get narrower and narrower as you get closer to these accounts running out of money,” said Rep. Rob Wittman (R-Virginia), the vice chair of the House Armed Services Committee. “Many of the places they’ve been able to go to get these dollars are running very thin now.”There has been an “uptick” in Pentagon reprogramming requests, which allow the department to shift money Congress approved, from one account to another, according to Sen. Chris Coons of Delaware, the top Democrat on the Senate defense appropriations subcommittee. Coons said that as he considers those requests, he has had to balance his opposition to Trump’s war with Iran and making sure that troops in the fight might run out of money, citing problems with the USS Abraham Lincoln’s extended deployment.

“I’m conscious that there is the possibility that if they are not able to reprogram some funding, you’ve got both Army and Navy units deployed that could run into shortfalls operationally,” Coons said. “I don’t want another USS Lincoln situation where you’ve got a lack of fuel and food.”

Hurst disputed the idea that the Pentagon is making substantially more or more urgent reprogramming requests than usual. Still, he acknowledged, “The kinds of things we’re programming might be a little different than normal.”If the extra money never materializes, some of the Pentagon’s plans could just take longer. Byron Callan, a Wall Street analyst at Capital Alpha Partners, expects some of the spending envisioned for reconciliation to be spread across defense budgets over the next five to eight years.

Key Democrats, such as Sen. Jack Reed of Rhode Island, say the uncertainty along all three funding tracks makes it more important that the Pentagon realistically identify its top priorities for Congress.

“What they have to do is put in a budget bill what they absolutely need,” said Reed, an appropriator and the ranking member on the Senate Armed Services Committee. “That will require them to compress their spending in some areas and expand in areas like munitions. We need to see a coherent plan, not three different initiatives.”