As the global pandemic and a staggering economic crisis swells, Dr. Mehmet Oz, the controversial celebrity doctor, has been advising senior Trump administration officials on coronavirus-related matters. Oz has even caught President Donald Trump’s attention with the celebrity doctor’s numerous appearances on the president’s favorite TV channel, The Daily Beast has learned.

In the past couple of weeks, Trump began hearing more and more about—and watching Oz, now a Fox News regular, discuss—hydroxychloroquine, an anti-malaria drug that Trump aggressively touted as a coronavirus treatment, much to the dismay of various medical experts and scientists. Over these two weeks, the president had specifically made a point of telling aides that he was interested in what Oz had to say and that he wished to speak to the much-maligned television personality, according to two people familiar with the president’s requests. It is unclear if Trump has spoken on the phone with Oz lately, as he told aides that he wished to do so.

But Trump has told officials that it would be “a good idea” if they talked to Oz, one of the sources added. Top administration officials, including Trump’s administrator of the Centers for Medicare and Medicaid Services, Seema Verma, have privately spoken to Oz in recent days to discuss the virus and his views on the possible treatment, three sources said. The New York Times first reported that Oz had been in touch with the Trump team.

Oz seemed to confirm his level of access to the administration during an interview with Fox & Friends hosts last week, saying an “astute question” that co-host Brian Kilmeade asked the other day “on this show” actually inspired him to contact Verma about using the Medicare and Medicaid national data to compare coronavirus infection rates in patients already prescribed hydroxychloroquine versus patients who are not taking the drug.

“It's a rough-and-tumble study, but she’s agreeing to do it, or look into it, anyway,” Oz claimed.

This is not necessarily a welcome development for some of the public health professionals on the president’s coronavirus task force. “It is very annoying to some of us that Dr. Oz is trying to poke his head in and get more involved in this,” said a senior administration official who works closely with the task force. “This shouldn’t be a celebrity showcase... Are we going to deputize Dr. Drew and Dr. Spaceman next?” (Dr. Leo Spaceman is a fictional lunatic doctor who was portrayed by actor Chris Parnell on the NBC sitcom 30 Rock.)

When asked about the use of hydroxychloroquine to treat coronavirus—Oz’s current cause—on Fox & Friends on Friday morning, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told the co-hosts that “although there is some suggestion with [a recent hydroxychloroquine] study that was just mentioned by Dr. Oz… I think we’ve got to be careful that we don’t make that majestic leap to assume that this is a knockout drug.”

At his coronavirus news conferences on Saturday and Sunday, Trump again hyped up the drug he has repeatedly labeled a “game changer.”

“I hope they use hydroxychloroquine,” he said. “What do you have to lose?” Trump added that 29 million doses of the drug were now available for doctors to use on COVID-19 patients. “I may take it,” Trump, who has twice tested negative for the coronavirus, said. “I have to ask my doctors about that.”

But Trump and Oz’s unproven claims about hydroxychloroquine have come at a cost to those that need it most—to patients with autoimmune diseases who rely on the drug. Healthy people started hoarding it after Trump’s promotion. In some cases, doctors were found to be writing prescriptions for family and friends who didn’t need it, leaving actual sufferers of lupus and rheumatoid arthritis down to only a handful of pills. One Arizona man died after ingesting the fish-tank cleanser chloroquine phosphate, reporting thinking it could help fight off the coronavirus, according to his widow.

Oz has appeared on Fox News 21 times since March 24, including a virtual town-hall event where he promoted hydroxychloroquine as a coronavirus treatment and got to speak directly to Trump and Vice President Mike Pence. Oz is still in the midst of a media blitz that has focused on swinging by some of the shows that Trump watches most obsessively.

Oz has made eight appearances on the president's favorite breakfast show, Fox & Friends, a program that has had concrete, recurring influence on his political and policy moves. The doc has been on Sean Hannity’s program seven times, twice on Lou Dobbs’ show, once on Morning with Maria, and once on Shannon Bream. Both Dobbs and Hannity serve as prominent informal advisers to Trump.

“The U.S. government has to procure enough of these pills,” Oz told Fox & Friends on March 23. “My biggest challenge was getting pills, and we finally, thankfully got enough to do a trial and a couple of hundred people, but America is going to want pills.”

Oz has not been seen in almost a month on NBC, where he had been part of the Today show’s so-called “Coronavirus Crisis Team.” NBC News did not respond to a request for comment on why Oz has been missing from its coverage.

Oz did not return repeated calls for comment on this story. A rep for The Dr. Oz Show didn’t respond to a comment request, either.

Oz has been labeled a “quack” from others in his profession and has repeatedly come under fire for his dubious medical advice pushing phony weight-loss remedies and saying that Umckaloabo Root Extract is a cure for the common cold. He has also had an obsession with genetically modified foods and the false theory that they are linked to cancer.

Three Mayo Clinic scientists—Dr. Jon C. Tilburt, M.D., and Ph.D.s Megan Allyse and Frederic W. Hafferty—slammed Oz in a February 2017 article in the AMA Journal of Ethics.

“Should a physician be allowed to say anything—however inaccurate and potentially harmful—so long as that individual commands market share?” they wrote. “In a professional sector whose history and growth is marked by the sustained and rightful denouncement of quacks and quackery… an inability to define and fence the epistemic boundaries of scientific medicine from apparent quackery on such a visible scale becomes something akin to a full-scale identity crisis for medicine…”

“He’s been dishonest and he has been dispensing misinformation to millions now for years,” physician and scientific researcher Henry I. Miller told The Daily Beast last month. “I wouldn’t trust any of his observations and don’t see how he would have responsible and valid views on coronavirus.”

But the controversy-courting TV doctor’s ascension in Trumpworld—at a time of a deadly, historic pandemic—was years in the making. Long before Trump was elected, the future president, then a reality TV star and real-estate businessman, and his family were personally acquainted with Oz via the Manhattan and celebrity social circuits. They exchanged small talk at parties and formal events over the years, two people who know both men recalled.

Toward the end of his 2016 face-off against Democratic presidential nominee Hillary Clinton, candidate Trump went on Oz’s show to discuss his health, saying it was a “great honor” to be on the long-running daytime talk show. When asked “how do you stay healthy on a campaign trail” by Oz, Trump replied, “I’m up there [at rallies] using a lot of motion, I guess in its own way, it’s a pretty healthy act. And I really enjoy doing it. A lot of times, these rooms are very hot, like saunas.”

Trump then added, “and I guess that’s a form of exercise, and, you know,” before trailing off. During this explicitly softball interview, the Republican nominee very gently moved his arms around to demonstrate the kind of “motion” that he deemed “exercise.”

By the middle of the Trump presidency, Oz’s proximity to the 45th president of the United States started paying off. In May 2018, Trump announced his plan to appoint Oz to the president’s Council on Sports, Fitness, and Nutrition.

Two years on, Oz hit a much bigger personal milestone in the Trump era: managing to worm his way into playing the role of informal adviser to the administration grappling with a near-unprecedented disaster. But the TV doctor isn’t the only person in Trumpworld pitching hydroxychloroquine, the supposed miracle drug, during the pandemic. A business group started by Trump megadonor and Home Depot founder Bernard Marcus has purchased Facebook ads to push for the adoption of the anti-malaria medication.

Rudy Giuliani, the president’s personal lawyer and a central figure in the Ukraine saga that triggered Trump’s impeachment, told The Daily Beast that he’d been talking about the coronavirus with Trump over the phone since last month. Giuliani declined to go into specific detail about what precisely the two men discussed. But online, the former New York City mayor has emerged as one of Trumpworld’s most aggressive advocates for hydroxychloroquine as a weapon against the coronavirus.

It got to the point late last month where Twitter began censoring the Trump attorney, removing one of his tweets promoting the treatment that was deemed egregious enough to be a violation of the social network’s rules.

—with additional reporting by Justin Baragona