President Donald Trump's nominee for Veterans Affairs secretary, Navy Rear Adm. Ronny Jackson, hit a roadblock after Senate lawmakers postponed his confirmation hearing amid multiple allegations stemming from his time as the White House physician.

Some of those allegations include claims of excessive drinking at work, creating a hostile work environment, and improperly dispensing medication. The claims come from “current or former White House medical staff,” according to a CBS News report published Monday night.

Business Insider has not independently verified the claims. Neither the White House nor the Veterans Affairs department immediately responded to requests for comment.

Related: The Prospective VA Chief Has An Extremely Ballsy Nickname »

“I can tell you we're vetting out Jackson,” Democratic Sen. Jon Tester of Montana told The Washington Post. “I can't get into specifics, but we're doing our job to make sure he's fit for the job.”

But two unnamed sources reportedly confirmed to CBS News correspondents that committee members were reviewing allegations against Jackson.

Jackson, who was originally scheduled for a Wednesday hearing in front of the Senate Committee on Veterans' Affairs, has already been under fire from some lawmakers who expressed doubt over the White House physician's ability to lead the nation's second-largest agency.

Jackson, who served as the White House physician under George W. Bush, Barack Obama, and now Trump, was thrust into the spotlight after performing Trump's first physical as president, and later delivering an effusive report on Trump's health.

Trump VA Nominee’s Confirmation Hearing Postponed Amid Disturbing New Allegations

White House physician Dr. Ronny Jackson speaks to reporters during the daily briefing in the Brady press briefing room at the White House in Washington, DC on Tuesday, Jan. 16, 2018.Getty Images/The Washington Post/Jabin Botsford

But despite being well-perceived in the White House, questions over his lack of sufficient management experience have clouded Jackson's nomination, which came shortly after the controversy surrounding the ouster of former VA secretary David Shulkin.

Shulkin was removed from his post in March after a series of scandals and rumors of infighting at the VA. He was the only Cabinet member unanimously confirmed by Congress.

It remains unclear whether Jackson's confirmation hearing will be rescheduled or scuttled completely, according to The Post.

“There's a need for very exacting and close scrutiny and vetting,” Democratic Sen. Richard Blumenthal of Connecticut said to The Post. “And some questions that need to be answered. I'm not going to comment on any of the specifics, except to say we're going to be doing very close and careful scrutiny.”

Read more from Business Insider: