Since its inception in 1977, the Energy Department has been responsible for managing America’s nuclear weapons, but a bill now before the Senate would strip the department of much of its budgeting authority over nuclear arms and hand it over to the Pentagon.

The measure has drawn quick criticism — even from within the Trump administration. Senators from both parties have joined Energy Secretary Dan Brouillette in arguing that the measure would upset the balance between civil and military officials regarding the country’s nuclear weapons program and would represent an unacceptable subordination of the Energy Department to the Defense Department.

“Holy cow, this is a big fight,” Sen. Maria Cantwell (D-Wash.) said Tuesday in an interview. She believes the Trump administration, over the objections of Brouillette, wants to direct more of the department’s money to building nuclear weapons, at the expense of cleanup programs and civilian uses of nuclear technology.

Her state is home to the Hanford Site, a decommissioned nuclear complex that is undergoing a lengthy cleanup, at a cost of $2 billion a year. She doesn’t want to see that financing stream cut.

A spokeswoman for the Senate Armed Services Committee, which included the provision on a 25-2 vote, disputed the assertion that the aim is to free up more money for weapons at the expense of other programs. “No authority has been stripped from the Energy Secretary whatsoever,” Marta Hernandez wrote in an email.

The bill is the defense authorization act for 2021, on which a vote is expected this week. The provision, similar to but stronger than one that was voted down in 2018, would require sub-Cabinet-level Pentagon officials to review budget plans for nuclear arms, and any increases they thought necessary would have to be reported onward without any changes by the energy secretary to the president’s budget writers. It would cover about 40 percent of the Energy Department’s total budget. Additional weapons spending would most likely be compensated by cuts in the remainder of the department’s budget.

“What the [act] does, through several provisions, is clarify and strengthen existing law that requires coordination between the Department of Defense and the [National Nuclear Security Administration, an agency under the Energy Department] on its budget development,” Hernandez wrote. “The existing mechanisms have not been effective, and in recent years, DOD has functionally not even seen the NNSA budget until after it is finalized and ready to transmit to Congress.”

The Defense Department would not be drawing up the nuclear arms budget from scratch or take over all budgeting authority, she said. “It simply clarifies the process for the future.”

In a letter to the head of the Armed Services Committee, Sen. James M. Inhofe (R.-Okla.), that he sent Monday, Brouillette wrote, “This, in effect, leaves the Secretary with responsibility for the program, while removing his or her ability to effectively manage it.”

Sens. Lisa Murkowski (R-Alaska) and Joe Manchin III (D-W.Va.) also objected to the provision. In a joint letter to Inhofe and the committee’s top Democrat, Sen. Jack Reed (R.I.), they argued that the change might appear to be a bureaucratic adjustment but that its effect would be significant.

“As written, these provisions would undermine and subordinate the Secretary of Energy’s statutory authority, including his or her responsibility to prepare a budget for congressional review, and would likely result in collateral damage for DOE’s nonweapons priorities,” they wrote.

The Pentagon would naturally emphasize nuclear arms, they predicted, at the expense of the cleanup of legacy defense waste sites, the cybersecurity of the electric grid and funding for energy innovation.

They also objected strongly to the way their own Energy and Natural Resources Committee was kept out of the loop.

The similar attempt in 2018, which also originated in the Senate, was voted down by the House of Representatives. Cantwell said that this time, it would be better to stop the move before it gets out of the Senate.

If the measure became law, she said, “What’s DOD going to do next year — go after State? USAID? Where does it stop? The more people get away with bad governance, the more they’ll keep trying.”

Over the weekend, the sense in Congress was that members in both chambers wanted to get the bill passed quickly and were relieved that there had been little partisan fighting over its provisions. Cantwell said she fears that too many members will be reluctant to vote against a defense bill and won’t take the time to understand the provision’s ramifications.