Donald Trump declared in a tweet that he’s nominating White House doctor Ronny Jackson to replace David Shulkin as secretary of veterans affairs.

....In the interim, Hon. Robert Wilkie of DOD will serve as Acting Secretary. I am thankful for Dr. David Shulkin’s service to our country and to our GREAT VETERANS! — Donald J. Trump (@realDonaldTrump) March 28, 2018

Shulkin’s ouster had been whispered about for months, the result of a European travel scandal and strained relations with the White House. But the president’s choice of Jackson was somewhat unexpected — and could potentially be contentious given his lack of management and policy experience.

Jackson had a brief stint in the spotlight after he delivered an effusive evaluation of Trump’s mental and physical health in a lengthy press conference after the president’s physical back in January. “It is called genetics. ... Some people have just great genes,” Jackson said during the briefing. “I told the president that if he had a healthier diet over the last 20 years, he might live to be 200 years old.”

Jackson’s glowing assessment of Trump’s health raised a few eyebrows, but the well-respected doctor has served two other presidents. Jackson served as a White House physician during the George W. Bush and Barack Obama administrations, and in 2013 Obama named him to the top job, physician to the president. Trump kept Jackson on in that role.

Jackson is also currently an active-duty one-star rear admiral (lower half) in the Navy. (Trump just nominated him for a promotion to rear admiral (upper half) last week, which would garner him a second star.) He’s been in the Navy since 1995 and was deployed to Iraq, where he served in a surgical shock trauma platoon.

But Jackson’s medical and military credentials won’t be under intense scrutiny during a Senate confirmation hearing for VA secretary; instead, he’ll likely be judged on whether he can run the second-largest US government agency.

Jackson said he would step down from active duty if confirmed, but beyond his military and public service, little is known about his policy views or his ability to manage a massive federal bureaucracy. Conservatives are pushing to privatize the VA, and Jackson — like Shulkin before him — will likely find himself smack in the middle of that debate.

“Ronny” might have gotten the job because of that physical

Jackson doesn’t appear to have vast bureaucratic management experience, but he checks off a lot of the Trump Cabinet résumé requirements: The president likes him, he has a distinguished military career, and he looks good on television.

According to Axios’s Jonathan Swan, Trump thinks highly of Jackson and delivered rave reviews about his performance during the press conference when he explained the president’s physical results. Jackson’s appearance seems to have made a lasting impression on Trump, reports CNN:

Trump’s positive impression of the military doctor had staying power, with Trump praising Jackson to donors during a fundraiser at Mar-a-Lago in February. ”He’s like central casting — like a Hollywood star,” Trump said, according to an audio recording of his remarks obtained by CNN.

Trump reportedly bragged to people about how smart Jackson was, and the two have a strong personal rapport, the Washington Post reports:

“I love the guy!” Trump often says of Jackson, who is referred to in the White House as “Dr. Ronny.” Trump sometimes calls him “The Doc.”

Trump values personal connections as much if not more than professional qualifications, and it seems Jackson has made quite the connection with the president.

Jackson might face a tough confirmation hearing

Jackson has won bipartisan respect for his distinguished career in medical and public service for Republican and Democratic administrations. But that might not be enough for him to overcome questions about his qualifications.

The outstanding question that looms over Jackson is whether he has the experience, or the capability, to manage a bureaucracy as vast and complicated as the Department of Veterans Affairs, which has a budget of nearly $200 billion.

Which is why veterans groups and some lawmakers on Capitol Hill are reportedly rattled by Trump’s choice.

“We’re really surprised at this nominee,” Joe Chenelly, national executive director of Amvets, a veterans advocacy group, told the Wall Street Journal. “Looking at his background we don’t see anything that indicates he’s capable of running a $200 billion agency. The VA is a lot more than just a medical system.”

Jackson also will likely be grilled at his hearing about privatization efforts at the VA, a contentious issue conservatives are pushing in Congress and within the department.

All of this points to a tough confirmation hearing for Jackson. Shulkin’s firing, while not totally unexpected, could leave the VA without permanent leadership for months. Trump has selected Robert Wilkie, the undersecretary of defense for personnel and readiness, to serve as acting secretary in the interim, but the staff turnover isn’t likely to bring stability to an agency that faces tremendous challenges serving its veterans.

“He cannot be a yes man,” Anthony Principi, who served as secretary of veterans affairs from 2001 to 2005 during the Bush administration, told Vox of Trump’s nomination. “He has to do what’s right for veterans. The VA is in turmoil and it needs stability.”

Alex Ward contributed to reporting.