WASHINGTON — Ronny L. Jackson, President Trump’s embattled nominee to lead the Department of Veterans Affairs, withdrew from consideration Thursday amid mushrooming allegations of professional misconduct that raised questions about the White House vetting process.

“The allegations against me are completely false and fabricated,” Jackson said in a statement. “If they had any merit, I would not have been selected, promoted and entrusted to serve in such a sensitive and important role as physician to three presidents over the past 12 years.”

Jackson’s nomination had become imperiled even before Capitol Hill Democrats on Wednesday released new allegations of professional misconduct. The claims include that Jackson, the White House physician, had wrecked a government vehicle after getting drunk at a Secret Service going-away party.

The allegations were contained in a two-page document described by the Democratic staff of the Senate Veterans’ Affairs Committee as a summary of interviews with 23 of Jackson’s current and former colleagues. The document also described Jackson’s “pattern” of handing out medication with no patient history, writing himself prescriptions and contributing to a hostile work environment with “a constant fear of reprisal.”

Veteran advocates and many lawmakers also had expressed concerns about Jackson’s lack of management experience, and some have worried that he would capitulate to President Trump’s goal of outsourcing more veteran services.

Jackson, 50, has denied wrongdoing. He told colleagues Wednesday night that he had grown frustrated with the nomination process, according to two White House officials with knowledge of his deliberations. He was a surprise nominee to succeed David Shulkin, an Obama-era holdover once lauded by Trump, who was fired March 28.

Jackson becomes the latest candidate Trump has put forward to run a major agency only to topple during the confirmation process. His prior nominees for labor secretary, Army secretary and Navy secretary all withdrew last year after questions arose during their vetting process.

Jackson’s nomination to lead the federal government’s second-largest agency was contentious from the start. White House officials, members of both political parties and veterans advocates all questioned the president’s decision, which was announced via Twitter on March 28.

The move coincided with Trump’s removal of Shulkin as VA secretary. The Cabinet’s only Obama-era holdover, Shulkin clashed with those in the administration who’ve sought an aggressive expansion of VA’s Choice program, which allows veterans to seek health care from private providers at taxpayer expense. Those opposed to that plan fear it will undermine efforts to address the many challenges VA faces.

Jackson, a one-star Navy admiral whose tenure at the White House spans three administrations, has been criticized as too inexperienced to take on the monumental task of leading an organization comprising more than 360,000 employees. Apart from overseeing the White House medical staff, Jackson led a military trauma unit in Iraq, tending to troops who had suffered catastrophic wounds during one of the war’s most violent stretches.

He rose to prominence in January, after delivering a fawning assessment of Trump’s health. The president is said to have been captivated by his doctor’s appearance in the White House briefing room, where, following Trump’s physical, Jackson extolled Trump’s fitness and cognitive acuity.

Late last week, aides to Sen. Jon Tester, D-Mont., the committee’s ranking Democrat, received damaging information about Jackson’s management of the White House medical office. They began interviewing his colleagues, many of them active-duty military officers, whose assessment of the admiral alarmed not only Tester but the committee’s chairman, Sen. Johnny Isakson, R-Ga., who agreed to postpone Jackson’s confirmation hearing while lawmakers investigated the allegations.

The report released by committee Democrats suggested Jackson demonstrated a “pattern” of handing out medication with no patient history, writing prescriptions for himself and contributing to a hostile work environment where there was a “constant fear of reprisal.” The document also says he “wrecked a government vehicle” after getting drunk a Secret Service party.

The White House, which was criticized for failing to adequately vet Jackson’s nomination, defended him until the end, saying that his record as a physician serving three presidents was unassailable, and demanding that he be allowed to defend himself during a confirmation hearing. But by Wednesday night, senators in both political parties doubted he could survive politically.

Since 2001, when the U.S. went to war in Afghanistan, VA has had seven secretaries. It’s acting head is Robert Wilkie, who was moved into the role from another appointed position at the Defense Department.

Veterans advocacy groups said this week that politics have precluded the agency from effectively addressing the many challenges it faces as health care needs grow for Vietnam-era veterans and those who have served since 9/11.

“This is complete and total chaos after years of complete and total chaos,” said Paul Rieckhoff, founder and chief executive of Iraq and Afghanistan Veterans of America, an advocacy group. “Our veterans deserve so much better. Our whole country does.”

Jackson planned to retire from the Navy to take VA job. Trump has put him up for a promotion from one-star to two-star admiral. That nomination remains pending with the Senate Armed Services Committee.

A leading veterans group said Thursday morning that it was happy to see the end of a “painful and tumultuous chapter” for Veterans Affairs.

“But the volatile, damaging saga continues,” said Rieckhoff. “We now face the prospect of a stunning eighth nominee for VA Secretary since 9/11. Our community is exhausted by the unnecessary and seemingly never-ending drama.”

The Post’s Emily Wax-Thibodeaux contributed to this story.

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