President-elect Trump made few campaign promises more passionately than his pledge to gut the mismanaged Department of Veterans Affairs and offer servicemen and servicewomen the dignified treatment they deserve, but his ability to deliver those results will likely depend on the people he chooses to lead the agency.

With more than 300,000 employees, the VA is the largest federal agency by personnel, aside from the Defense Department. It is the fifth-largest agency by budget. And much of that sprawling bureaucracy has succumbed to backlog, waste and even corruption as veterans increasingly find themselves waiting longer for worse care.

"We think it is absolutely critical that you have somebody as VA secretary that has the backbone and the courage to stand up to the VA bureaucracy," said Dan Caldwell, vice president of policy at Concerned Veterans for America. "You need someone who understands how entrenched and how resistant to change many mid-level and upper-level managers in the VA are."

Caldwell said the current VA secretary, Robert McDonald, was "almost instantly absorbed" by the bureaucracy of the department and "sadly, [he] became its biggest defender."

Trump has not yet indicated who might be on his list of contenders for VA chief. As of Monday, he has only filled the top jobs at the CIA and the Department of Justice.

However, Rep. Jeff Miller, chairman of the House Veterans Affairs Committee, is rumored to be under serious consideration for the job. Other names floated for the position include former Govs. Rick Perry and Mitt Romney, the latter of whom is most often discussed in connection with Secretary of State.

Whoever takes the helm of the VA will have a daunting task ahead of them to implement the sweeping reforms Trump spent the past year promising to bring to the broken agency. On Obama's watch, the VA suffered the biggest scandal of its 86-year history when whistleblowers exposed the existence of secret patient waiting lists in 110 facilities around the country.

Those secret lists concealed the fact that thousands of veterans were enduring long stretches of time before they could see a doctor. Some veterans died while they waited.

In the aftermath, VA Secretary Eric Shinseki was forced to resign, his ouster billed as a preview of the personnel purge that would restore the agency to its mission.

But that purge never happened. Most VA employees caught manipulating wait-time data were simply suspended, reprimanded or left untouched. The VA only fired nine people over their involvement in the nationwide scheme.

Miller, who is retiring from the House in January, said Trump's VA reform proposals amount to "basic common sense," which he said VA leaders have rejected.

"The prospects for Department of Veterans Affairs reform under a Trump administration are significant," Miller told the Washington Examiner. "Instead of trying to sugarcoat VA's challenges like the Obama administration has done for much of the last eight years, President-elect Trump will fight hard to overcome them. And instead of catering to the special interests that are blocking efforts to address VA's number one problem – its notorious lack of accountability – President-elect Trump has made clear that reforming the department's broken civil-service system is a top priority."

Miller has said he would be open to running the VA if Trump offered him the position.

However, a Miller aide said the job is not his primary focus.

"Right now, Chairman Miller is focused on being chairman of the House Committee on Veterans' Affairs and representing Florida's 1st Congressional District," the aide told the Examiner. "He is fully supportive of President-elect Trump's vision for reforming the Department of Veterans Affairs."

Beyond the wait-time scandal, the agency has struggled to scale back out-of-control spending on efforts from art collection to hospital construction.

Conditions at many clinics have deteriorated, such as the Chicago-area facility that became infested with cockroaches or the Wisconsin clinic that turned veterans into addicts by dramatically over-prescribing narcotics.

Meanwhile, commonsense reform legislation has stalled in the Senate as federal employee unions have taken exception to anything that gives VA leadership more powers to fire staff.

Amanda Maddox, a spokeswoman for Sen. Johnny Isakson, said the Senate Veterans Affairs Committee he chairs "by nature will still operate in a bipartisan fashion on legislation that can get the requisite 60 votes to pass the Senate" in the coming session of Congress.

"We are looking forward to working with the new House leadership, our new ranking member in the Senate and a new administration to hit the ground running next year on reforms that will help improve access to top-quality care, benefits and support for our veterans," Maddox told the Examiner.

While Miller appears to be the rumored frontrunner in the VA secretary selection process, Perry and Romney have also been mentioned as people Trump has considered for the appointment.

David Carney, a former longtime aide to Perry, said the former Texas governor would be an "excellent choice" to "build [the VA] from the basement back up."

"I don't know that he's interested in it, but I know that he would be an excellent choice," Carney said. "If you need something reformed, he's the guy that will not let the status quo stand in the way."

Perry is himself a veteran, having served as a captain in the Air Force. He briefly challenged Trump for the Republican nomination, but dropped out early in the GOP primary.

Ryan Williams, a former Romney campaign aide, said the former Massachusetts governor would also make a capable VA secretary.

"Gov. Romney has a long history of restructuring organizations to make them work better," Williams said. "The governor is someone who, while being very compassionate, always wants to make sure that any organization he's managing is run as efficiently and as successfully as possible."

During the presidential race, Trump's VA reform proposals centered on the quality of his pick for head of the embattled veterans agency. The first priority on his 10-point plan to fix the VA was to "appoint a VA secretary whose sole purpose will be to serve veterans," according to his campaign website.

His other proposals include the creation of a commission to investigate the instances of waste, fraud and abuse that have plagued the agency, as well as the establishment of a "private White House hotline" that will allow veterans to log their VA-related complaints directly with his office, 24 hours a day.

Caldwell, who suggested Miller would be a particularly wise choice for the job, emphasized the importance of carefully filling the positions directly under the VA secretary.

"The undersecretary positions and the deputy secretary positions are just as important as who is appointed VA secretary," he said, adding that the VA chief would need strong officials to help "battle the entrenched bureaucracy."