Shulkin’s ouster comes amid a wave of resignations and dismissals in the Trump team’s senior ranks, following the departures of economic adviser Gary Cohn, National Security Adviser H.R. McMaster and Secretary of State Rex Tillerson, all announced this month.

Shulkin, 58, a doctor and former hospital administrator, took office in February 2017 following a unanimous vote by the Senate. He was the sole holdover in the Cabinet from the Obama administration. He served as undersecretary for health overseeing medical facilities run by the VA, which provides care for more than 9 million enrolled veterans.

Shulkin had been under fire for a European trip that included a tennis outing at Wimbledon, accounts of troubling conditions at medical facilities, reports of tension with his senior staff, and friction over plans to shift care to the private sector.

Trump announced the change in a tweet.

I am pleased to announce that I intend to nominate highly respected Admiral Ronny L. Jackson, MD, as the new Secretary of Veterans Affairs….

— Donald J. Trump (@realDonaldTrump) March 28, 2018

“I am pleased to announce that I intend to nominate highly respected Admiral Ronny L. Jackson, MD, as the new Secretary of Veterans Affairs,” Trump said. “I am thankful for Dr. David Shulkin’s service to our country and to our GREAT VETERANS!”

Jackson, a naval officer, has been a White House physician since George W. Bush’s presidency. His nomination will require Senate approval.

He conducted Trump’s first official medical exam as president in January and declared Trump “fit for duty.”

Questions about Trump’s fitness for office had flared at the time after a book — “Fire and Fury” by Michael Wolff — asserted that many of Trump’s senior aides thought the president mentally unwell. Jackson reported that a screening of the president’s cognitive function, designed to check for signs of dementia or Alzheimer’s disease, was normal.

Shulkin came into office with a pledge to bring greater accountability to the agency and to improve veterans’ access to care, and not to privatize the department.

In July 2017, he traveled to Denmark and England with senior Veterans Administration officials, his wife, and a six-member security detail, according to a February report by the agency’s inspector general. The 11-day trip included three and a half days of official events and cost at least $122,334, the report said. It found that Shulkin improperly accepted two tickets to the ladies’ final match at Wimbledon.

Shulkin told lawmakers that he regretted decisions “that have been made that have taken the focus off” the VA’s work, and said he would reimburse costs as recommended by the inspector general, who called for repayments for the Wimbledon tickets and the airfare for the secretary’s wife.

Shulkin’s trip was among several involving top Trump administration officials to draw notice. Environmental Protection Agency Administrator Scott Pruitt relied on first-class flights, racking up a $1,641.43 bill for a trip between Washington and New York, and Health and Human Services Secretary Tom Price stepped down over flights with a total cost that exceeded $1 million.

The report of Shulkin’s travel stoked tensions within the agency, and he reduced contacts with Trump’s political appointees and installed an armed guard outside his office, according to a March 9 report in the Washington Post. The discord centers around plans to direct more spending on veterans’ care to private facilities than Shulkin favors, according to a Feb. 16 ProPublica report.

On March 7, the VA inspector general released a report that said “failures in leadership” led to critical deficiencies at the agency’s Washington medical center, where inventories weren’t properly maintained and patient records weren’t securely stored. At times, doctors had to borrow supplies from a nearby hospital, according to the report. Shulkin told interviewers he didn’t recall senior officials bringing the center’s problems to his attention when he was undersecretary overseeing medical facilities, according to the report.

Asked about the report, White House Press Secretary Sarah Sanders on March 7 said Shulkin “has done a great job.”

Robert Wilkie, currently the undersecretary of for Personnel and Readiness at the Defense Department, will serve as acting secretary for Veterans Affairs while Jackson awaits Senate confirmation, Trump said.