White House physician Ronny Jackson withdrew from consideration as secretary of the Department of Veterans Affairs early Thursday, prompting a statement from Sen. Jon Tester, who said the nominee faced serious accusations about his workplace conduct.

The allegations, which Jackson labeled as false, included odd prescription drug practices, a toxic work environment and drunkenness while on duty.

A summary of those allegations, collected through conversations with nearly two-dozen colleagues and former colleagues of Jackson, prompted Tester and Sen. Johnny Isakson, R-Ga., to postpone the nominee's scheduled hearing this week before the Senate Committee on Veterans Affairs.

That pressure culminated Thursday with Jackson withdrawing from consideration.

“It is my constitutional responsibility to make sure the veterans of this nation get a strong, thoroughly vetted leader who will fight for them,” Tester said Thursday morning. “The next Secretary must have a commitment to reform a strained health care system and a willingness to stand up to special interests who want to privatize the VA.”

Following Jackson's withdrawal, former secretary of defense and former U.S. Sen. Chuck Hagel, R-Neb., defended Tester's vetting process and his dedication to veteran issues.

Hagel is Vietnam veteran and former deputy administrator of the VA.

"I know who the real leaders are in the veterans world and who are looking out for the interests of veterans and their families," Hagel said in a statement Thursday. "There is no one who cares more about veterans and looks out for their interests than my former colleague, Jon Tester.

"As a veteran who has had the privilege of serving my country in many capacities, I’ve always admired Jon Tester’s commitment to helping veterans – not using veterans for political purposes.  Veterans know who their champions are, and Jon Tester is one of them.”

Tester, who said he'd continue working with Isakson to vet and confirm a more appropriate VA secretary, also urged Congress to continue investigating the White House Medical Unit, which Jackson led.

After postponing Tuesday’s hearing, Tester and Isakson sent a letter to President Donald Trump seeking all information regarding improper conduct pertaining to Jackson’s service in the unit and as physician to the president.

“We further request any and all allegations and documents, including those developed during the course of an investigation, that are in the custody of the White House Military Office, the White House Medical Unit, or any office in the Executive Office of the President that were never communicated to the Department of Defense or Offices of Inspector General,” the letter states.