The Defense Department supports legislation floated by Sens. John McCain and Jack Reed that would authorize a new round of military base closures around the country and set up a clash with the House, Lucian Niemeyer, a newly appointed assistant defense secretary who oversees installations, said Tuesday.

The chairman and top Democrat on the Armed Services Committee have drafted the legislation as a possible amendment to the Senate's annual defense policy bill that will be debated on the chamber floor this month. But the House and McCain's Armed Services counterpart in that chamber, Rep. Mac Thornberry, R-Texas, have long resisted a round of closures under the Base Realignment and Closure program, or BRAC.

Niemeyer, who spoke at the Heritage Foundation, said authorization to close unneeded facilities could save money and also allow the department to prepare for a new generation of military technologies as it conducts a defense strategy review, echoing years of Pentagon requests to reduce the roughly 20 percent of military facilities that are considered excess.

"For us, it's not just a matter of finding efficiencies, it's a matter of improving the military value and the effectiveness and lethality of our military forces," he said. "That's why we continue to push hard, and we support the Senate's attempt to try to get a BRAC authorization inserted into the [2018] defense authorization act."

The Trump White House has also called for shuttering unneeded bases.

The McCain and Reed proposal, which was circulated in Washington in July, places a $5 billion cap on the closures and directs them to start by 2021, according to various reports.

McCain, who underwent brain cancer treatment over the summer, is expected to return to the Senate this week to continue work on proposed amendments to the National Defense Authorization Act and to shepherd the bill through a vote on the floor.

The BRAC proposal could be put up for consideration as an amendment to the NDAA and McCain's support could add some needed momentum for proponents, said Andrew Hunter, a senior fellow at the Center for Strategic and International Studies.

"BRAC always is hard, and it's not popular, it's not something Congress likes to do, and so the key element is there has to be a champion," Hunter said. "There has to be someone in Congress who is highly respected who is really taking this on and pushing it forward."

Even if it passes the Senate, it would likely face steep opposition in the House, where many members have been unwilling to even consider closures that could end jobs and hurt local economies in their districts.

The House passed a security "minibus" of spending bills in July that bars any closures and approved its version of the NDAA after knocking down attempts at amendments that would have opened the door to BRAC.

Meanwhile, Thornberry has long opposed a BRAC round, saying upfront costs of closures do not always result in advertised savings, and will be sitting across from McCain when the top Republicans and Democrats of the two armed services committees hash out a final version of the NDAA later this year.

A cap on spending for any future round of closures as McCain and Reed have proposed could be "basic grounds for compromise" with Thornberry and other reluctant House members, Hunter said.

Neimeyer also said it would not be unusual for Thornberry to strike a compromise during upcoming NDAA conference negotiations following Senate passage of its final version of the bill.

"As a veteran of 11 national defense authorization conferences, there's also the ability for him to give up on one thing in order to get something else," said Neimeyer, who is a former Senate Armed Services staff member.