Separately, CNN reported members of the committee had been told of allegations of improper conduct in his past.
Dorsey noted that Sen. A spokeswoman for the Veterans Affairs Committee didn't respond to a request for comment. In an interview with The Washington Post before the allegations were made public, Tester said the committee is "doing our job to make sure he's fit for the job".
Two Republican sources with direct knowledge of the situation say the White House is aware that both Democratic and Republican lawmakers are looking into potential problems.
White House physician Dr. Ronny Jackson speaks to reporters during the daily press briefing in the Brady press briefing room at the White House, January 16, 2018. "That's the process of vetting that has to occur", said Sen. Richard Blumenthal of CT said to The Post. We are working very hard at it. "And some questions that need to be answered. And then we're gonna see what we can come up with and go from there", Tester said.
Ronny Jackson was tapped to replace ousted Veterans Affairs Secretary David Shulkin. Shulkin faced ethical issues and tensions with political appointees within the agency and the White House.
While Jackson is an active-duty Navy admiral who has been the physician to the president since 2013, various lawmakers have raised concerns over his fitness to run the VA, which is the second-largest government bureaucracy.
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. Mock hearings were held throughout the weekend, aides said, trying to prepare Jackson for Senate questioning. But Jackson gave the president top rating.