Dr. Anthony Fauci talks about the challenges of advising former President Trump on COVID

Dr. Anthony Fauci sat down with the co-hosts of "The View" to discuss advising Former President Donald Trump during the pandemic's peak, serving under seven presidents as NIAID director and the Latin phrase that has guided his work.

Fauci was the director of the National Institute of Allergy and Infectious Diseases from 1984 to 2022. During the pandemic, he was a key White House Coronavirus Task Force member and initially had a good working relationship with Trump.

However, the dynamics of their relationship shifted when Trump began say things that were "not true," according to Fauci. Fauci, driven by what he said is a strong sense of personal and professional integrity, found himself at odds with the former president, a situation he says was not easy for him to navigate.

As Fauci attempted to implement policies recommended by the Centers for Disease Control and Prevention, he claimed that Trump and his supporters opposed him.

ABC News sat down with Fauci to talk about his deteriorating working relationship with Donald Trump during the COVID-19 pandemic.

ABC NEWS: So before we start, people are so glad to see you. They are so glad to see you.

FAUCI: Thank you.

ABC NEWS: So thank you for coming on the show and for everything. Everything you've done from the very beginning. It's extraordinary. And you're no worse for the wear. You look good.

FAUCI: Thank you.

ABC NEWS: You say empathy has always guided you as a physician and a public servant, but there's also a Latin phrase that has consistently come up for you and I'd love you to share it and tell everybody what it means.

FAUCI: Well, when I was getting my education in high school, Latin and Greek was an important part of our classical training. It was actually at Regis High School, a few blocks from here, a Jesuit school. And one of the things that they mentioned to us when things got down and you felt the world was caving in on you was Illegitimi non carborundum, which means 'Don't let the bastards wear you down.' Boy did that hold true.

ABC NEWS: You know, you look, you are probably one of the classiest people I've ever watched move around in Washington, D.C.

FAUCI: Thank you

ABC NEWS: So and -- you know, I just want to raise my dreads to you. But I don't want to take up too much time, Alyssa.

ABC NEWS: Well, Dr. Fauci, it's so good to see you. Before retiring from government in 2022, you served under seven presidents and bipartisan administrations. Fighting diseases like AIDS, Ebola, and, of course, COVID-19, where you and I got to know each other. You had addressed so many of these ailments before and never faced the backlash that you did from part of the country when you were working on COVID. Did you see that coming? We watched it in real time.

FAUCI: No, it was really unexpected. Because, as Alyssa said, I served and advised seven presidents, Democrat and Republican, both sides of the aisle. There are always disagreements, of course. But that's why we have a great country because you have people with different ideological views.

But the disagreements were always associated with civility, with respect for each other and respect for institutions in the government. So you could have a disagreement, but at the end you try and compromise. What happened with COVID, as I think was represented by the hearing a few weeks ago, was just pure ad hominem and vitriol. And that really took me by surprise. I thought there would be the give and take and respect each other's disagreements.

That's the thing that worries me not only about what I have to face, but also about the direction of the country and the social order of the democracy. It's very threatening I think.

ABC NEWS: It's in jeopardy. It's in jeopardy, I think. So you dedicate a chapter of your book to your dealings with Trump, the chapter is called "He loves me, he loves me not" and you describe some angry ranting expletive-filled phone calls. He would berate you and flatter you in the same breath. I'm wondering: you said you worked with seven other presidents. Did any one of them ever speak to you the way he does or did?

FAUCI: No, of course not. Not even close. What I meant by loves me, loves me not. Early on in the beginning -- he is an engaging character and we had a certain rapport with each other. I was trying to figure out what it was. I think it was two guys from New York City. He was from Queens, I was from the Bronx and we kind of had that New York -- he calls it swagger -- with each other, that was fine.

And all that was really good in the beginning. Until you know, he wished and hoped that the outbreak would disappear because it clearly was getting in the way of both the economy and then, as a result of that, into the election cycle. So he started to say things that actually were not true. And I just felt that I had a responsibility for my own personal and professional integrity, but also my responsibility to you, the American public, so had to contradict him.

It was very difficult for me to do that. Once I did that, then things got really dicey. Because I don't think he went away from the fact that we did have a good relationship, but he was really very upset about the fact I had to get up and say, no, it's not going to disappear like magic and no, hydroxychloroquine doesn't work no matter what Laura Ingram is telling you. I mean that's the problem.

ABC NEWS: He doesn't like when people disagree with him. That's why cohorts in the Republican Party are kowtowing to him because they know it displeases him.

ABC NEWS: Well, speaking of hydroxychloroquine, countless of Americans lost loved ones to COVID. My husband lost both of his parents, two doctors, within three days of each other from the pandemic.

We remember those pandemic briefings. I remember the injection of bleach, perhaps. The hydroxychloroquine. Dangerous recommendations. You were particularly disturbed, I read, by his refusal to wear a mask.

What was this time like for you having to contradict the president of the United States? And what should everyone know about how he handled the crisis? Because I blame him for my in-laws' death.

FAUCI: Well, the people who became very angry with me, people on his staff like Peter Navarro and Mark Meadows, and others thought that I was doing that because I had some sort of antipathy to the president and I did not. It was very painful for me. I have a great deal of respect for the presidency of the United States of America. I served seven presidents; it wasn't like 'wow, isn't this cool I'm contradicting the president.' It was very very painful, but I had to do it.

With regard to the masks, the thing that was a problem, is that when the CDC came out and made the recommendations -- indoors we should be wearing masks. That was at a time when the infections were going like that. And what he got up and said it's recommendation but I'm not going to do it; I choose not to do it. I consider that a missed opportunity to use the bully pulpit of the presidency to get people to do things that was for their own safety.

He has millions and millions of followers who are very loyal to him. All he had to do is say the CDC is recommending masks; we know it's going to save lives, do it. He missed an opportunity.

ABC NEWS: I remember telling him he looked cool in the masks because I thought that might be like, 'Fine. I'll wear it.' Didn't work.

FAUCI: Nice try, Alyssa.