After weeks of confusion atop the Department of Veterans Affairs, President Trump dismissed its secretary, David J. Shulkin, on Wednesday and announced he would replace him with the White House physician, Dr. Ronny L. Jackson, a rear admiral in the Navy.
If confirmed, Dr. Jackson, a career Naval officer who has no real experience running a huge bureaucracy, would inherit a set of challenges that have trusted Democratic and Republican administrations alike. The department, the federal government’s second biggest, has been burdened for years by aging infrastructure, an inefficient health care system and an unwieldy 360,000-person work force.
He could also rapidly face crucial, multibillion-dollar decisions over the replacement of its outdated computerized records system and legislation that would ease the rules around veterans searching private health care at government expense.
The announcement punctuated what has been a rapid fall from favor for Dr. Shulkin, a politically moderate former hospital executive who delivered Mr. Trump a string of bipartisan legislative victories at a time when he was struggling to find them. But in his final weeks, he struggled to fight off attempts by more conservative administration officials to have him removed and was dogged by an unflattering inspector general report on his overseas travel that undermined his relationship with the president.
Dr. Shulkin’s departure was the latest chapter in the remaking of Mr. Trump’s team of senior advisers, a shake-up that has led to the replacement of the secretary of state, the director of the C.I.A. and the national security adviser, along with White House aides.
In the midst of that turmoil, Dr. Jackson, 50, who was named to his current position by President Barack Obama in 2013, has grown close with Mr. Trump, a commander in chief who enjoys similar faces in his orbit and often rewards them with new roles.
Dr. Jackson had a rare turn in the spotlight in January, when he announced the results of Mr. Trump’s physical, his first while in office, and addressed speculation over the president’s physical and mental health. The president was very pleased with the performance.
“I’ve found no reason whatsoever to think the president has any problems whatsoever with his thought processes,” Dr. Jackson said.
His policy views are all but unknown, though, especially on Capitol Hill, where the Senate will decide whether he is up to leading the department. Senators, including Johnny Isakson of Georgia, the chairman of the Senate Veterans Affairs Committee, issued cautious statements on Wednesday praising Dr. Shulkin and indicating that they would need to get to know the nominee.
That tone was echoed by mainstream veterans groups like Disabled American Veterans and the American Legion, who hold considerable sway in Washington, and who warned of a potential leadership vacuum at the department.
Privately, several White House aides acknowledged that Dr. Jackson’s lack of managerial experience could be problematic and said that once again the president’s interest in his personal bond with someone was more significant than their curriculum vitae.
In a Twitter post on Wednesday announcing the changes, Mr. Trump called Dr. Jackson “highly respected” and thanked Dr. Shulkin for “service to our country and to our great veterans.”
Mr. Trump said that Robert Wilkie, the under secretary for defense personnel and readiness at the Defense Department, would serve as acting secretary in the meantime, bypassing the department’s deputy secretary, Thomas G. Bowman.
The White House did not respond to a request asking who would replace Dr. Jackson.
Dr. Shulkin, who served as under secretary of veterans affairs in the Obama administration, had started to make headway on some of the department’s most persistent problems. Those included an expansion of the G.I. Bill for post-9/11 veterans, legislation that makes it simpler for the department to remove bad employees and a law that streamlines the appeals process for veterans seeking disability benefits.
Those successes and his easy grasp of complicated policy problems won Dr. Shulkin deep support on Capitol Hill and among veterans groups. And Mr. Trump, who made veterans issues and overhauling the scandal-ridden department a focal point of his campaign, showered Dr. Shulkin with praise. At a bill-signing ceremony in June, the president teased that the secretary need never worry about hearing his “Apprentice”-era catchphrase, “You’re fired.”
“We’ll never have to use those words on our David,” Mr. Trump said. “We will never use those words on you, that’s for sure.”
But in recent months, a group of conservative Trump administration appointees at the White House and the department began to break with the secretary and plot his ouster. At issue was how far and how fast to privatize health care for veterans, a long-sought goal for conservatives like the Koch brothers.
The officials — who included Dr. Shulkin’s press secretary and assistant secretary for communications, along with a top White House domestic policy aide — came to consider Dr. Shulkin and his top deputy as obstacles.
The secretary’s troubles only grew when what had been an internal power struggle burst into the open in February, after the department’s inspector general issued a scathing report on a trip Dr. Shulkin took last year to Britain and Denmark. The report, describing what it called “serious derelictions,” found the secretary had spent much of the trip sightseeing and had improperly accepted Wimbledon tickets as a gift.
Critics of the secretary seized on the report to try to hasten his removal. Dr. Shulkin, fearing a coup, went public with a warning about officials “trying to undermine the department from within” and cut off those he saw as disloyal. The efforts backfired. At the White House, senior officials came to trust that Dr. Shulkin had misled them about the contents of the report. And the secretary’s public declarations only further aggravated top officials, who felt Dr. Shulkin had gone too far in commenting on internal politics with news outlets and had opened the administration to sharp criticism over his trip to Europe, which the report said cost more than $122,000.
But as recently as early March, after meetings with John F. Kelly, the White House chief of staff, Dr. Shulkin publicly claimed victory, signaling that he had the White House’s support to remove officials opposing him.
The victory was short-lived. Before long, Dr. Shulkin sharply curtailed his public profile, cutting off communications with reporters and isolating himself from top deputies he viewed as disloyal. People who have spoken with the secretary in recent days said he was determined to keep his post, even as it became increasingly clear his time was up. He was set to meet with leaders from the nation’s largest veterans groups on Thursday.
Despite his problems with the White House, Dr. Shulkin remained overwhelmingly popular on Capitol Hill, where the Senate unanimously confirmed him last year, and among the veterans groups that have traditionally held outsize influence in Washington. In recent weeks, leaders from both parties publicly and privately signaled their support, even as rumors of his replacement appeared in news reports.
But Mr. Trump had had enough. He began to discuss successors in recent weeks, even considering Energy Secretary Rick Perry as a possibility. He told friends last weekend that he would fire Dr. Shulkin, it was just a question of when.
Dr. Shulkin had made a preliminary inquiry about having Dr. Jackson for an under secretary role last year, and the president spoke with him briefly about it then, one senior administration official said. But it went nowhere at the time.
By Monday, Mr. Trump had started animatedly talking with a handful of people about the idea of Dr. Jackson’s replacing Dr. Shulkin, people similar with the discussions said. Still, he did not tell many advisers of his plan until soon before it was announced.
A Navy doctor since 1995, Dr. Jackson deployed as an emergency medicine physician to Taqaddum, Iraq, during the Iraq war. He has served as a member of the White House medical unit since 2006 and as its lead physician since 2013, overseeing Mr. Obama’s physicals.
Dr. Jackson had told several people that he planned to retire from Washington after Mr. Obama left office. But Mr. Trump, whose previous personal physician made headlines with a series of unauthorized news interviews about his patient, asked Dr. Jackson to stay on. Mr. Trump, who goes to great lengths to hide details of his personal life, quickly came to trust Dr. Jackson, referring to him warmly as “Doc” around the White House.
Democrats, moderate Republicans and mainline veterans groups have all feared that Dr. Shulkin’s departure could clear the way for a more aggressive push for government-subsidized private care at the department.
“Every major veterans’ organization in this country vigorously opposes the privatization of the V.A.,” Senator Bernie Sanders, independent of Vermont and a member of the Senate Veterans Affairs Committee, said in a statement. “I stand with them. Our job is to strengthen the V.A. in order to provide high-quality care to our veterans, not dismember it.”