Internal Pentagon drama is strangling D efense Secretary Ash Carter’s signature initiative to make the military’s promotion system function more like a Fortune 500 company, leaving the controversial reform effort unlikely to succeed during the Obama administration's final months.

The Defense Department's most senior military and civilian leaders have spent months debating a detailed plan to rewrite the policy governing how military officers are promoted, part of a slate of reforms known as "Force of the Future." The idea is to end the "up-or-out" rules that force mid-career officers to leave the military if they fail to be promoted along rigid timelines, providing flexibility to pursue non-traditional career tracks or focus on developing technical expertise. But now the effort has stalled amid acrimony, finger pointing and disagreements .

At issue are reforms to the officer personnel system that would end the "up or out" rules that force mid-career officers to leave the military if they fail to be promoted along rigid timelines. As proposed, the change would give officers more flexibility, allowing them to pursue non-traditional career tracks or focus on developing technical expertise.

The standoff is outlined in a recent internal memo, a copy of which was obtained by Military Times. In a series of follow-on interviews, several insiders elaborated on the strife. All spoke on the condition of anonymity because the matter remains unresolved. It's evidence, they say, of the Pentagon's crippling bureaucracy, especially on personnel matters, which historically have been relegated to the services to manage independently.

Some officials blame the breakdown on opposition from the military service chiefs, who generally support the traditional personnel system that defined their own careers. They reject the premise that today's system is "broken." Others say it's due to Carter's waning interest, that he underestimated the deep controversy his efforts have fueled. Critics also fault the Pentagon’s former personnel chief, Brad Carson, who resigned abruptly in April after spending much of the past year aggressively pushing these reforms and attacking the current system.

A spokesman for the Joint Staff declined to comment for this story, as did Carson.

A spokesman for the secretary said that Carson’s departure will not slow the reform effort.

"Secretary Carter is full speed ahead on Force of the Future," said Peter Cook. "He very much appreciates Brad Carson's substantial contributions to this effort, but this has always been about more than any one individual. This is about making sure the secretary's successors have the same access to great talent that he does currently."

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Photo Credit: Staff Sgt. Bernardo Fuller New Under Secretary of the Army Brad R. Carson gives remarks during his swearing-in ceremony at the Pentagon, May 9, 2014.

Brad Carson resigned from his Pentagon job in April after growing frustrated with the lack of movement on his recommendations for modernizing the military's personnel system.

Photo Credit: Staff Sgt. Bernardo Fuller/Army

Carson, the memo's author, spent months urging senior military leaders to agree on a compromise, leading a complex coordination effort with all of the individual military leaders, including the four-star service chiefs, the three-star personnel chiefs and their staffs. A former Navy officer as well as former U.S. Representative for the state of Oklahoma, he left in frustration after Carter refused to sign off on his final reform recommendations, according to several defense officials familiar with the internal deliberations.

His memo advocated the following :

Formally asking Congress to suspend laws imposing across-the-board up-or-out rules. The recommendation says the defense secretary should seek to shift this authority to the Army, Navy, Air Force and Marine Corps, allowing each to determine how many times an officer can be passed over for promotion before mandatory separation. The changes would offer flexibility for non-traditional career paths, especially for those officers who want to spend more time developing technical expertise rather than preparing for high-level command assignments.

Formally asking Congress to grant the Pentagon more flexibility regarding how many years of service an officer must accumulate before facing a promotion board. This would allow individuals more flexibility to pursue non-traditional assignments — such as being a Rhodes Scholar (as was Carson); spending several years working in the private sector or taking family leave — without jeopardizing their careers. It would also clear the way for top performers to receive early promotions.

Formally asking Congress to suspend its caps on the number of officers allowed to serve in the military's "control grades," or the O-4 through O-6 paygrades, and shift authority to the individual services to shape the force based on individual needs.

Formally asking Congress to lift the requirement that officers must retire at 30 years of service if they are not promoted to general or admiral, and instead grant the individual services authority extend careers up to 40 years.

Carson spent months urging senior military leaders to agree on a compromise. He led a complex coordination effort with all of the individual military leaders, including the four-star service chiefs, the three-star personnel chiefs and their staffs.

The secretary has said the reforms are necessary to appeal to millennials and ensure the military continues to recruit and retain the best and brightest young people. But the effort fueled an internal battle that centered on two distinct schools of thought.

It found supporters in the Navy and the Air Force, where officers want time to develop more technical expertise and some prefer honing those skills rather than preparing for senior-level commands. Those services have a diverse array of career fields, many with professional counterparts in the civilian sector that invite non-traditional career paths.

Yet the reforms were opposed by many leaders in the Army and the Marine Corps, where the service cultures focus more on traditional leadership. The combat arms career fields are more homogeneous, have fewer counterparts in the private sector and arguably do little to encourage alternative career paths.

The debate over personal reform has revealed the Pentagon's crippling bureaucracy, especially on personal matters that have historically relegated to the services to manage independently.

In his memo, Carson, 49, said those disagreements were resolved, telling the secretary these detailed proposals were "agreed to by all the military and civilian leadership of the military departments."

Some Pentagon officials say that's false, and that concerns and disagreements remain. "There are still some people in the services who are uncomfortable with this," said one senior defense official. "Fairly or unfairly, some viewed Brad as trying to jam them."

Amid the internal battle, the secretary appointed a new personnel chief, Peter Levine. A longtime Capitol Hill staffer, he spent years smoothing over disagreements created by annual defense spending .

Levine is revisiting substantial pieces of the personnel reforms, going back to the individual service leaders to rehash their concerns and potentially rework the proposals that Carson left on the secretary’s desk.

"That is going to take time," said one Pentagon personnel official. Levine plans to " make sure we have a package that not only people in the department feel that they’ve had a chance to work on and contribute to, but that they’re happy with."

Carson declined to comment for this story.

A spokesman for the secretary said Carson's departure will not slow down the reform effort.

"Secretary Carter is full speed ahead on Force of the Future. He very much appreciates Brad Carson's substantial contributions to this effort, but this has always been about more than any one individual. This is about making sure the Secretary's successors have the same access to great talent that he does currently," said Pentagon spokesman Peter Cook.

Major changes would require approval from Congress, where things have not gone well to date. Carson received a hostile reception at a February appearance before the Senate Armed Services Committee. Republican Sen. John McCain, committee chairman, blasted the proposed personnel reforms as "an outrageous waste of official time and resources" and several times during the hearing accused Carson of lying.

Now the clock is ticking. Congress has begun drawing up its annual defense authorization bill, and so far its plans do not include any of these personnel reforms.

The Pentagon is acutely aware the window of opportunity is closing. Officials have initiated back-channel communication with Congress in case there's a last-minute shot at fast-tracking the legislative process if and when the defense secretary makes a decision.

"We've talked to Capitol Hill about it and let them know what may be coming so that we can preserve the option of working on it. ... I don't think we're foreclosed from taking legislative approach where we need to [this year]," the personnel official said.

What went wrong?

Carter’s focus on personnel reform initially came as a surprise. A lifelong civilian with a doctorate in physics, the secretary spent much of his career in the Pentagon’s business and policy divisions.

Yet shortly after taking over the Defense Department's top job, Carter began talking about overhauling the military personnel system to appeal to millennials. He signaled a desire to change the up-or-out rules proscribed under the 1980 law known as the Defense Officer Personnel Management Act, or DOPMA.

Carter also expressed displeasure with the military's joint billet requirements mandated under the 1986 Goldwater-Nichols Act, which Congress passed in the wake of the Vietnam War in an effort to force the parochial services to coordinate more effectively on the battlefield. Many experts believe today’s joint force functions well and that the law is outdated. The law requires mid-career officers to spend at least 36 months in a job assignment officially designated as "joint" before they can be eligible for promotion to general or flag officer.

He questioned the traditional military rank structure and said mid-career civilians should be allowed to join the military without starting at the lowest rungs of the personal system. He said he wanted to create a military personnel system that "let people pause their military service for a few years — while they're getting a degree, learning a new skill, or starting a family."

Yet those ambitious goals have largely faded from his public remarks during the past several months. Some say the secretary bit off more than he could chew and underestimated how passionately career military professionals were going to feel about these personnel policies.

Coincidentally, the personnel reform effort came to a head at about the same time that Carter was signing off on new rules allowing women to serve in combat for the first time. Although it was a policy change initiated by a predecessor, Carter made the final call on that controversial issue, a move that strained his relationship with some senior military leaders. Some personnel experts inside and outside the military think that may have limited his willingness and ability to lobby in favor of his own personnel reforms.

"I don't think he really knew what he was getting into when he announced Force of the Future, said one observer familiar with Carter's efforts. "I don't think the secretary had a good appreciation for how passionately people were going to feel about this."

In addition, Carter has had his hands full managing President Obama's controversial strategy for fighting the Islamic State group in Iraq and Syria while balancing several other sensitive operations around the world — in Afghanistan, in Eastern Europe and in the South China Sea .

US Secretary of Defense Ashton Carter speaks during a press briefing at the Pentagon in Washington, DC, March 25, 2016. The Islamic State group's second in command has been killed in a US raid in Syria, Pentagon chief Ashton Carter confirmed March 25, 2016, in a move he said would hamper the operational ability of the jihadists. "The removal of this ISIL leader will hamper the ability for them to conduct operations inside and outside of Iraq and Syria," Carter told reporters of the death of Abd ar-Rahman Mustafa al-Qaduli, referring to him as Haji Imam and saying he served as finance minister for the group. / AFP / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

Defense Secretary Ash Carter

Photo Credit: Saul Loeb/AFP/Getty Images

Personnel reform, although important to Carter, just doesn't have the same priority, said one person familiar with the internal discussions. "I think it's hard to focus on this kind of stuff when you're talking about counter-ISIL and dealing with two-hour meetings with [National Security Advisor] Susan Rice. It's hard to reorient yourself and say 'How do I make an ensign's life better?'"

Another source of friction was Carson himself, officials said. Immediately after taking over the job of undersecretary for personnel and readiness, Carson assumed an unusually public role as an advocate for reforms, talking about today’s "industrial-era" personnel system being "broken" and comparing it to "a Polaroid in the time of digital cameras."

His style was in stark contrast to his predecessors within the Pentagon's office of personnel and readiness who rarely spoke publicly or advocated for policy change.

It's not going away

While Carson earned praise from many personnel experts as a smart and hard-working reformer, others criticized his approach as too aggressive. One Pentagon official said his coordination with individual military leaders was "awful" and that Carson relied heavily on a small group of advisers, leaving many senior military leaders feeling like they had only limited input in the process. His departure may help clear the way for his reform effort to ultimately succeed, one defense official said.

"Maybe he overreached," said Tim Kane, a military personnel expert and author of the book "Bleeding Talent: How the US Military Mismanages Great Leaders and Why It's Time for a Revolution."

Kane strongly supports the efforts to change the up-or-out rules that are imposed under the Defense Officer Personal Management Act, or DOPMA, which he called "the root of all evil."

"It creates this one-size-fits-all career track. It doesn't allow people to specialize," Kane told Military Times. "What if you have someone who is a cyber-warrior and they just want to be a hacker? Maybe they don't want to command a squadron. But 'up-or-out' kind of forces everyone in the officer corps to be on the command track."

Carson's work forced the top brass to take a hard look at the personnel system, which will likely have a lasting impact on the politics inside the Pentagon.

The proposal may not make it to Capitol Hill this year, Kane added, but there's no reason why the next defense secretary and the next president — regardless of whether it's a Republican or a Democrat — can't continue the effort. The issue is not going away.

"This," Kane said, "is not partisan issue."

Staff writer David Larter contributed to this report.