White House says Trump will defend VA nominee hours after he suggested he step aside Dr. Ronny Jackson's confirmation hearing Wednesday has been postponed.

Hours after President Donald Trump suggested his embattled nominee to head the Department of Veterans Affairs, Rear Adm. Ronny Jackson, should step aside, the White House is now saying the president will fight for him.

"The president will be defending him," White House Director for Legislative Affairs Marc Short told ABC News just moments after Jackson emerged from a late afternoon meeting with Trump at the White House.

A White House official added that Jackson will not be withdrawing his name from consideration.

Those comments came after the president said Jackson, his White House physician and hand-picked nominee to head the VA should withdraw his name from consideration.

"I wouldn't – if I were him, actually in many ways I'd love to be him, but the fact is I wouldn't do it. I wouldn't do it," Trump said in the East Room of the White House during a joint press conference with French President Emmanuel Macron.

"What does he need it for? To be abused by a bunch of politicians that aren't thinking nicely about our country? I really don't think personally he should do it, but it's totally his. I would stand behind him. Totally his decision," Trump said.

The Senate Veterans Affairs Committee is reviewing what it calls "serious allegations" surrounding Jackson that include claims he created a hostile work environment and improperly dispensed medication as a White House physician, congressional and administration sources tell ABC News.

The sources said the medication in question is the prescription sleep aid Ambien.

Committee leaders announced Tuesday that they had postponed Wednesday's confirmation hearing while they reviewed the allegations.

Republican Sen. Jerry Moran of Kansas met with Jackson Tuesday on Capitol Hill and told ABC News that Jackson said that he has denied the allegations.

"He does deny that he's done anything wrong in his service to the country and particularly his time at the White House as a physician in the Medical Unit," Moran said. "I think the proper thing to do is not to reach any conclusions. The admiral indicated he was very anxious for his hearing and would like to respond to the allegations, although my impression is he doesn't know exactly what they are either."

As part of its defense of Jackson, the administration has just released official copies of 2012 and 2013 "command climate assessments" for the White House Medical Unit as well as signed performance reviews of Jackson by Presidents Obama and Trump. “Dr. Jackson is a great doctor + leader – ‘ 2-star material,” President Trump wrote in his own handwriting in a 2017 fitness report and counseling record.

The administration says that the claims against Jackson of a hostile work environment result from a personal feud Jackson had with another doctor in the White House Medical Unit -- a dynamic which was ultimately resolved and morale improved, according to one of the assessments.

“Dr. Jackson’s record as a White House physician is impeccable," a senior administration official said. "He has improved unit morale, received glowing reviews and promotions under Republican and Democrat presidents, and has been given a clean vet from the FBI. He has never even been the subject of an Inspector General review and he will certainly not be railroaded by a bitter ex-colleague who was removed from his job.”

Earlier this afternoon, just moments before the president suggests he not go through with the confirmation process, ABC News spotted Jackson on Capitol Hill meeting with lawmakers about his nomination. He ignored questions about the allegations and said, "I'm looking forward to re-scheduling the hearing and getting the process moving."

Asked whether the hearing would be rescheduled he said, "That's going to be up to the committee."

President Trump praised Jackson as "a fine man" and a "great doctor, great everything," but said wouldn't want Jackson to go through a politically damaging nomination process.

"I don't want to put a man through who's not a political person. I don't want to put a man through a process like this," Trump said. "It's too ugly and too disgusting. So we'll see what happens. He'll make a decision."

Trump also addressed concerns that Jackson, who is currently the president's personal White House physician, lacks the overall management qualifications to head the second largest agency in the federal government, saying simply "there's an experience problem."

In a letter to Trump, the top Republican and Democrat on the committee ask the White House to turn over "any and all allegations and documents, including those developed during the course of an investigation" related to Jackson's service in the White House Medical Unit.

Democratic Sen. Richard Blumenthal, a member of the Veterans Affairs Committee, would not discuss details of the allegations but told ABC News "they go to his integrity and his management ability and his credibility to manage that department."

Committee chairman Republican Sen. Johnny Isakson shared concerns about the allegations but cautioned to ABC News "not everything you read in the news is true."

The White House was standing by the nomination of Jackson earlier Tuesday, but senior aides concede privately that there is a chance the nomination goes down.

Deputy secretary Hogan Gidley released a statement Tuesday morning on Jackson after news of the allegations broke, saying "He's served as the physician to three Presidents—Republican and Democrat—and been praised by them all.

"Admiral Jackson’s record of strong, decisive leadership is exactly what’s needed at the VA to ensure our veterans receive the benefits they deserve,” the statement said.

Jackson has spoken publicly about prescribing Ambien during White House international trips, a common practice for overcoming jet lag. "When we travel from one time zone to another time zone on the other side of the planet, I recommend that everyone on the plane take a sleep aid at certain times so that we can try our best to get on the schedule of our destination," Jackson said at a press briefing earlier this year.

Several lawmakers said the White House should be held responsible for the delayed nomination because of a failure to properly vet the nominee.

"It is really frustrating to me that this administration continues to not vet or sloppily send over a nominee that leaves us having to really vet them and look at serious questions, which this Senate is now doing, and that's the right step," Sen. Patty Murray, D-Wash., told ABC News.

Asked if he should withdraw his nomination, she said, "that is up to the White House."

"But I will assure you that every one of us as members of the committee are looking at every allegation and we have a responsibility to do so," she said.

President Trump nominated Jackson last month after he fired his first VA secretary, David Shulkin, amid allegations Shulkin misused taxpayer funds and faced growing tension with other senior Trump staff.