The summary cited by the Times is based on testimony from 23 current and former colleagues of Jackson.

Jackson also allegedly wrote himself prescriptions, and after he was caught doing so he asked a physician assistant to provide the medication, The New York Times reported , citing a Democratic Senate staff summary of alleged conduct by Jackson.

Jackson, who is Trump's personal physician in the White House, also said his nomination is "still moving ahead as planned" before walking away from reporters.

After that story was published online, Jackson told reporters he "did not wreck a car."

Dr. Ronny Jackson, President Donald Trump 's embattled pick for Veterans Affairs secretary, allegedly provided a "large supply" of the opioid Percocet to a White House staffer, and wrecked a government car while intoxicated, according to a bombshell new report.

The report comes as Jackson's nomination for the VA post is already imperiled. Previously, there were allegations that he oversaw to a hostile work environment and drank alcohol on the job. There were already concerns about his experience and skill set for the job before the purported incidents were reported.

Jackson's appearance before the Senate committee reviewing his nomination, which was supposed to happen Wednesday, was postponed because of the claims.

But the White House aggressively defended Jackson on Wednesday, saying that at least four background investigations had found no areas of concern.

However, the Times story that cites the Democratic summary says that Jackson's medical staff was thrown "into a panic" when that unit could not locate missing Percocet. It turned out, according to the report, that Jackson allegedly gave the drugs to a military office staff member at the White House.

The article says Jackson's alleged wrecking of a government car came after he became intoxicated at a Secret Service going away party.

The summary also says that while accompanying President Barack Obama on an overseas trip in 2015, Jackson returned to a hotel after a night of drinking and banged on a staff member's door so loudly that the Secret Service warned him he was risking waking up Obama.

During another Obama-era trip, White House staffers who went to Jackson's room for medical reasons "found him passed out in his hotel room after a night of drinking," according to the story, citing aides to Sen. Jon Tester, D-Mont.

CNBC's Eamon Javers contributed to this report.