President Donald Trump praised his embattled White House doctor and insisted the allegations against him were false during a news conference on Friday.
"Ronny Jackson is one of the finest men I've ever met," Trump said at a news conference alongside German Chancellor Angela Merkel.
Trump said he explained to Jackson and his family that "Washington can be a very mean place."
"These were false accusations about a great man," he said.
Jackson withdrew his nomination to lead the Department of Veterans Affairs Thursday morning in response to an avalanche of allegations of questionable behavior.
Prior to his withdrawal, Senate Veterans Affairs Committee members were assessing allegations from whistleblowers who have told the panel about Jackson's questionable behavior including excessive drinking and a "toxic" work environment under his leadership, according to two former White House medical staff members who have spoken with the committee.
Trump lambasted Sen. Jon Tester, D-Montana, over the two-page list of allegations compiled against Jackson, describing it as a "disgrace."
"I think it's something we learn from. I called him today. I said in a certain way ... in a very big way, you're an American hero because you're exposed the system for some horrible things," he said.
"I've had it happen to me with the Russian collusion hoax. It's a hoax," he went on. "But I came into the job understanding that things happen. He didn't. He's a great doctor. He's a great admiral."
In withdrawing his nomination Thursday morning, Jackson said the range of allegations made against him were "completely false and fabricated."
"If they had any merit, I would not have been selected, promoted and entrusted to serve in such a sensitive and important role as physician to three presidents over the past 12 years," he said. "In my role as a doctor, I have tirelessly worked to provide excellent care for all my patients. In doing so, I have always adhered to the highest ethical standards."
CNN reported Friday, after Jackson withdrew, that the White House medical unit under his watch frequently functioned as a "grab and go" clinic where mid-level staffers to the most senior officials could obtain prescription drugs without being examined by a doctor, according to five of the medical unit's former and current employees.