By Gregory Hellman, 03/07/2017 04:10 PM EDT

Supporters in Congress of a new round of military base closures plan to propose that an independent commission not be authorized to make recommendations until at least 2021 — to give members of Congress maximum political cover and the Pentagon more time to study how much capacity it will need.

Adam Smith, the ranking Democrat on the House Armed Services Committee, introduced legislation last month that would allow the department to begin shuttering bases in 2019 based on the recommendations of a Base Realignment and Closure commission.

The bill has picked up nine co-sponsors, while Senate Armed Services Chairman John McCain (R-Ariz.) and top Democrat Jack Reed (D-RI) have both publicly called for a consideration of a new Base Realignment and Closure Commission, which the Pentagon has been seeking for more than five years.

But Smith is in the process of revising his legislation to  provide breathing room to lawmakers with targeted districts and give the Defense Department time to figure out how many bases it will need following the Trump administration’s proposed military building, according to congressional sources speaking on condition of anonymity.

President Donald Trump and Defense Secretary Jim Mattis have yet to make any public statements in support of base closures and a Pentagon spokesman declined to comment on the possibility.

But closing bases could provide the Trump administration with a vehicle to live up to its promise of cutting military waste — and some expect the Pentagon to seek a new round of military base closures in its 2018 budget request later this spring — as it has, to no avail, for five years.

Air Force and Army leaders recently expressed support for BRAC in congressional testimony, while others who have briefed the administration said that BRAC offers the department its best chance to shift resources to higher priority programs and reduce the civilian work force.

The second ranking officers in the Army and Air Force testified on Capitol Hill last week that they would support a new BRAC round. Combined, the services estimated they have a $36 billion backlog of infrastructure maintenance costs.

Tackling such inefficiencies will be paramount as Trump seeks to expand the size of the military, they added.

“[The administration] has strong beliefs in how poorly run the Pentagon and the intelligence community is,” said Mackenzie Eaglen, a defense fellow at the conservative American Enterprise Institute. “They believe there’s rampant waste, fraud, and abuse. But there’s just not a lot of big dollars without BRAC.”

Shuttering would free up funding for the president’s promises to expand the military, added Dakota Wood, a defense fellow at the conservative Heritage Foundation.

“From a businessman’s perspective, there’s a very strong business case for pursuing something like BRAC,” Wood said. “The Trump administration has made a really big case for rebuilding the military. If I’m looking for dollars, I’d look at facilities I don’t need.”

A new round of BRAC could also help the administration eliminate federal jobs by closing unneeded facilities, a goal the president embraced in issuing a hiring freeze last month, an analyst for the government-funded Rand Corporation said.

“The next round will be less about changing where the department does business and more about how,” said the analyst, who was not authorized to speak publicly. “I would be very surprised if the current administration with the support of Congress doesn’t try to reconvene [a commission].”

Last year the Defense Department completed a report that concluded overall the Pentagon has 22 percent excess overhead, including bases and other facilities.

It concluded that it could save as much as $2 billion a year from a round of base closures.

But it used the projected force structure of 2019 — before the election of Trump and his pledge to rebuild the military by increasing the size of the Army, build more Navy ships and invest more in the nuclear arsenal.

The majority of that excess capacity comes from the Army and Air Force, which each reported 33 percent and 32 percent excess, respectively. By contrast, the Navy and Marines only reported seven percent excess capacity.

House Armed Services Chairman Mac Thornberry (R-Texas) said he will not consider supporting a new round of BRAC until the Defense Department delivers a new report assessing the capacity of America’s military — one based on 2012 levels, before the Budget Control Act imposed across-the-board cuts, his spokesperson said.

“The capacity report the Pentagon belatedly delivered to Congress simply doesn’t tell us what we need to know,” Thornberry said in a statement.

The department has promised the House Armed Services Committee it will complete a revised report by this spring, a congressional aide said.

However, the chairman already left the door open for a new round by requesting the study, Eaglen said.

“Thornberry can be pushed,” she said. “It’s going to depend on how much wheeling and dealing the secretary is willing to do.”

But if the administration seeks to capitalize on any momentum on the Hill, it will also face a political minefield. Key members of both armed services committees are pushing back against a new BRAC round — especially in light of the president’s proposed military buildup.

“I’ve been through every BRAC round, five of them. Without exception, every BRAC round the first three years costs money,” SASC Readiness Subcommittee Chairman Jim Inhofe (R-Okla.) said at a hearing last month. “If there’s ever a time in the history of our military where we can’t afford to dilute those dollars that we need … it’s now.”

“Mr. Chairman, I just want to be clear for the record that I agree with your position,” Sen. Jeanne Shaheen (D-N.H.) echoed.

Despite opposition from Inhofe and Shaheen, any successful proposal for a new round of base closures will inevitably be driven by the Senate. House members remain too weary of political blowback, sources told POLITICO. One possible scenario is that McCain and Reed could win agreement for a new BRAC in conference negotiations for the defense authorization bill, a legislative aide said.

Those proposals will face particularly strong opposition from Northeastern legislators, like Shaheen. The last BRAC round, which occurred in 2005, originally targeted eight bases for closure in Massachusetts, Connecticut, Rhode Island, New York, New Jersey and Pennsylvania.

“I know how mobilized the citizenry of New England will get about this,” Eaglen said. “Once a target, always a target.”

But what is becoming increasingly clear is that if there is enough support in Congress and at the White House to authorize a new base closure round, it won’t actually start until after the next presidential election — which means years more of preparations by local communities.

“I think the best way to prepare for whatever comes is to every day do the best you can to support the installations in your area,” said retired Rear Adm. Craig Quigley, executive director of the Hampton Roads Military and Federal Facilities Alliance in southeastern Virginia, which hosts of number of of Army, Navy, Marine Corps and Air Force Installations.

That includes helping “to mitigate weaknesses and correct them wherever possible[and] to highlight strength wherever you can so that if the day comes when the Congress approves a BRAC you are as prepared as you can humanly be,” he added.