The person who initiated a slew of allegations against Rear Admiral Ronny Jackson was a holdover from the previous administration, according to report by investigative reporter Sara Carter.

Jackson, the physician for the past three presidents, was nominated by President Donald Trump to head the Veteran Affairs Department.

But then Senator Jon Tester (D-Mont.) circulated a list of anonymous allegations against Jackson, including claims that Jackson created a hostile work environment and in some instances behaved unprofessionally. Tester said the allegations came from Jackson’s current and former colleagues.

Jackson called the allegations “completely false and fabricated,” but still withdrew, saying the situation has become a distraction for Trump.

The main allegations came from Dr. Jennifer Peña, according to four administration officials’ account to Carter.

Peña has been with the White House Medical Unit since 2014 and was last year assigned by the unit as a physician to Vice President Mike Pence.

“Pena has had a long-standing feud with doctor Jackson…she’s very jealous that he’s been consistently promoted. This isn’t about being a whistleblower—there are other procedures for that. She went up to the hill and she spoke with approximately twenty-five Democrats…she’s a holdover in the White House and didn’t want Jackson to be nominated,” one of the officials said.

None of the allegations against Jackson have been substantiated. On the contrary, some of the allegations have been checked and denied by the Secret Service and the White House. Many who have known and worked with Jackson have since spoken out in his defense denying having seen any of the alleged behavior.

There’s also no sign any of the allegations have been reported before or shown up during the FBI’s thorough background checks on Jackson.

Jackson, 50, has worked as a presidential physician since the Bush administration and has been the lead doctor for Trump as well as former President Barack Obama. He is well-liked by both Republican and Democratic administration officials.

White House spokeswoman Sarah Sanders said Jackson was on the job at the White House on Thursday but it was not immediately clear whether he would resume his post as the top White House physician.

The Iraq war veteran gained national attention after he was attacked by media organizations in January following his annual assessment of Trump’s health. Jackson had said Trump’s health was excellent and that he had no concerns over the president’s cognitive ability, which ran counter to the narrative much of the media were trying to portray of Trump.

Trump criticized Tester for smearing the physician.

“Allegations made by Senator Jon Tester against Admiral/Doctor Ron Jackson are proving false,” Trump wrote on Twitter Saturday morning, April 28. “The Secret Service is unable to confirm (in fact they deny) any of the phony Democrat charges which have absolutely devastated the wonderful Jackson family. Tester should resign.”

“The great people of Montana will not stand for this kind of slander when talking of a great human being. Admiral Jackson is the kind of man that those in Montana would most respect and admire, and now, for no reason whatsoever, his reputation has been shattered. Not fair, Tester!”

The Veterans Affairs Department has long been under fire for the quality of healthcare it provides veterans. During his election campaign, Trump vowed to clean it up.

Trump fired former Veteran Affairs Secretary David Shulkin in March after concerns about unauthorized travel expenses.

Tester’s seat will be contested in the Nov. 6 midterms. Trump carried Montana in the 2016 elections with over 56 percent, compared to Hillary Clinton’s less than 36 percent.

Trump told Fox & Friends over the phone on Thursday that he liked Jackson as a candidate in part because he isn’t a politician. After this experience, however, he said his new candidate, yet to be announced, has “political capabilities.”

Trump later posted an update on Twitter.

“Secret Service has just informed me that Senator Jon Tester’s statements on Admiral Jackson are not true. There were no such findings. A horrible thing that we in D.C. must live with, just like phony Russian Collusion. Tester should lose race in Montana. Very dishonest and sick!