WASHINGTON — Lawmakers are taking another look at possible changes to the military’s “up-or-out” rules for officer promotions.

The idea has been widely discussed in the Pentagon and Congress in recent years, but likely would not amount to a full overhaul of promotions process, according to lawmakers who discussed the policy during a Senate hearing on Wednesday.

Instead, military officials and congressional staffers are looking at targeted changes to the system — things like increased waiver authorities or exemptions for certain career paths — in an effort to modernize aspects of military recruiting and retention.

“Today’s system largely serves its intended purpose,” said Sen. Thom Tillis, R-N.C., and chairman of the Senate Armed Services Committee’s personnel panel. “But a personnel system is not an end to itself. It must achieve desired objectives to increase the lethality and effectiveness of the force.”

Any changes to the nearly 40-year-old Defense Officer Personnel Management Act could have dramatic effects on military culture and careers, where promotions are mainly based on seniority and general experience instead of specific subject-matter expertise. Individuals who aren’t selected for career advancement on a rigid timeline are pushed out of the ranks completely.

Pentagon leaders have lamented that the rules hurt retention of some valuable mid-career officers whose specific skill sets make them ineligible for promotion but invaluable for specific missions.

They also prevent bringing in experts to tackle specific challenges — issues like cybersecurity — because individuals don’t have the requisite time in service to step into senior leadership roles.

“Today’s force is constantly engaged in ways never predicted during the Cold War,” Tillis said. “Repeated overseas combat deployments strengthened more traditional warfighting career fields, while at the same time new military domains require entirely different officer skill sets.”

Still, proposals from the Pentagon for reforms to the current system have stalled out on Capitol Hill in recent years. Former Defense Secretary Ash Carter’s “Force of the Future” proposals, which included changes to how promotions and recruiting authorities, were mostly rejected by lawmakers.

Military officials at Wednesday’s hearing said they are open to more flexibility with the promotion rules, but warned against a wholesale overhaul of the current system.

Lt. Gen. Gina Grosso, deputy chief of manpower for the Air Force, said service officials have already implemented a new officer performance management system designed to produce a more “thoughtful” promotions process.

Navy officials created a new Office of Talent Optimization last year with a similar goal of better linking officer skills with job assignments.

Army Deputy Chief of Staff Lt. Gen. Thomas Seamands called the current system “a framework that is effective for an Army of interchangeable parts,” but said he would like to see more opportunities managing key skills within officer grades.

Lt. Gen. Michael Rocco, deputy commandant for Marine Corps manpower and reserve affairs, said any changes must keep in mind the fundamental cultural needs of the services.

“The Marine Corps depends on our foundational schools, training and (tours) to increase skills and infuse our ethos and warrior culture,” he told the panel. “Any guidance to bypass these … would be a significant change in Marine Corps officer management philosophy and should be approached carefully.”

Lawmakers have not offered any specific changes yet. But the hearing was designed to revive debate on the topic again ahead of the committee’s upcoming work on the fiscal 2019 defense authorization bill, which annually includes a host of budget and policy priorities.