UPDATE: WASHINGTON — Dr. Ronny Jackson, the White House physician tapped by President Donald Trump to head the troubled Department of Veterans Affairs, withdrew his nomination on Thursday amid a flurry of allegations against him, including being drunk on the job and improperly doing out prescription drugs. 

"While I will forever be grateful for the trust and confidence President Trump has placed in me by giving me this opportunity, I am regretfully withdrawing my nomination to be Secretary for the Department of Veterans Affairs," Jackson said in a statement.

Jackson called the accusations against him "completely false and fabricated."

Unfortunately, because of how Washington works, these false allegations have become a distraction for this President and the important issue we must be addressing – how we give the best care to our nation's heroes," he said.

Jackson, the White House physician who shared the results of Trump's annual physical with the press earlier this year, had faced growing allegations of misconduct, including improperly handing out prescription drugs, being intoxicated on the job, and creating a toxic work environment.

Trump called into Fox News on Thursday to rip Jackson's critics.

"He would have done a great job," the president said. "Tremendous heart. These are all false accusations. They're trying to destroy a man. By the way, I did say, 'Welcome to Washington. Welcome to the swamp.'"

Trump also slammed Sen. Jon Tester, D-Mont, the ranking member of the Senate Veterans Affairs Committee, with going public with some of the allegations against Jackson.

"I think Jon Tester has a big price to pay in Montana," Trump said on Fox.

Jackson's confirmation hearing had been scheduled for Wednesday, but was postponed amid concerns over the allegations of inappropriate behavior. He is at least Trump's 24th unsuccessful nominee to a post that requires Senate confirmation, according to an NBC News tallly.

On Wednesday, congressional Democrats released additional details of allegations of improper conduct involving Jackson after speaking with nearly two dozen current and former colleagues of his — most of whom the committee said are still in uniform. The Democrats said those interviewed "raised serious concerns about Jackson's temperament and ethics, and cast doubt on his ability to lead the second-largest agency in government."

According to a two-page summary of the interviews released by the panel's staff, the White House medical unit had "questionable record keeping" for the medications it was distributing under Jackson's leadership. On one occasion, Jackson was said to have provided a "large supply" of the opioid drug Percocet to a staffer for the White House Military Office, which threw the office "into a panic" because it didn't know where the drugs went.

In addition to concerns about his prescribing practices, the summary noted "multiple incidents of drunkenness on duty," including one instance when Jackson could not be reached when he was needed "because he was passed out drunk in his hotel room." It added that Jackson once got drunk at a Secret Service going-away party and "wrecked a government vehicle." It did not note the year of the incident.

The White House had nevertheless stood by Jackson as recently as Wednesday, with multiple top Trump aides expressing their support for him publicly — even after Trump himself, on Tuesday opened the door for him to withdraw his nomination.