Transcript for New allegations facing VA nominee Ronny Jackson

We are following breaking developments at this hour involving president trump's personal physician, the president's pick to lead the V.A. There are new allegations revealed tonight. Ronny Jackson is accused of recklessly proibing an opioid. Just a short time ago, admiral Jackson was fighting back. What he's now saying. ABC's Mary Bruce is on the hill for us again tonight. Reporter: Toxic, abusive and volatile. Tonight, that's how some former and current colleagues are describing the president's pick to lead the V.A. Accounts from more than 20 people provided to ABC news by the top Democrat on the veterans affairs committee paint an explosive picture of Dr. Ronny Jackson. One describing him as, quote, "The most unethical person I have ever worked with." Have you seen any concrete evidence? We've talked to a number of folks that have made these claims. And we need to find out if it's true or not. Reporter: Jackson is accused of drinking on duty. On one occasion, when traveling with the president, he allegedly could not be reached when needed because he was "Passed out drunk in his hotel room." And at a party, he allegedly got "Drunk and wrecked a government vehicle." There are also accusations about Jackson's prescribing practices. He once allegedly gave a "Large supply" of percocet, a prescription opioid, to another staffer without documenting it, throwing his staff "Into a panic." When traveling on air force one, physicians and nurses describe him handing out ambien to help people sleep and provigil to help them wake up, earning him this nickname -- The candy man. Because he doled out prescription drugs like can down these trips where they flew through multiple time Zones. Reporter: We talk to some who say that's standard operating procedure, to make sleeping AIDS, for instance, available on long trips. Well, all I've got to say is, that if that's standard operating procedure, I have not witnessed it nor have I participated in. Reporter: Late today, as these new details emerged, Jackson was spotted at the white house. Asked about prescribing that percocet, he denied it. I have no idea where that's coming from. Reporter: And wrecking a government car? He denies that, too. It should be very easy to prove that. I have not wrecked a car. Reporter: Before these new bombshell allegations came out, the white house spent the day defending Jackson. Dr. Jackson has had at least four independent background investigations conducted during his time at the white house. The investigations revealed no areas of concern. Reporter: But she couldn't say if they vetted him again before nominating him to lead the V.A. When was his most recent background check? I'd have to look at the specific date, but my understanding is that a new one took place at the time of the new administration. Reporter: There were already serious questions about whether the president's personal physician can manage the government's second-largest agency, with a budget of nearly $200 billion. It was a suggestion, now, I know there's an experience problem, because lack of experience. Reporter: Today, the white house insisted Jackson is the right person for the job. If he didn't think he had the experience, he wouldn't have nominated him. He said that had been one of the questions people had posed about him. So, let's get to Mary Bruce, live up on the hill for us. And Mary, the white house says Ronny Jackson was thoroughly vetted in the past. They claim more than most nominees, in fact. And that none of these issues were raised? Reporter: David, we heard the white house press secretary today say Jackson received, quote, glowing evaluations, and that no red flags were ever raised. The white house says these sweeping allegations simply never came up before he was nominated. And we've just learned that Jackson is on his way back up here to the hill to meet with lawmakers again. Jackson still making his case. David? Mary Bruce live on the hill. Mary, thank you.

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