Dr. Anthony Fauci, the nation's top infectious diseases expert, said Sunday that earlier efforts to stop the spread of the coronavirus in the U.S. "obviously" could have saved lives but that top health officials faced "a lot of pushback about shutting things down."

Fauci, director of the National Institute of Allergy and Infectious Diseases, was responding on CNN's "State of the Union" to a New York Times report saying President Donald Trump's top public health officials concluded by the third week of February that they should recommend to the president a new approach to COVID-19 that included social distancing steps. But according to The Times, the White House "focused instead on messaging and crucial additional weeks went by before their views were reluctantly accepted by the president — time when the virus spread largely unimpeded."

"We look at it from a pure health standpoint," Fauci said on CNN. "We make a recommendation. Often, the recommendation is taken. Sometimes, it's not. But ... it is what it is. We are where we are right now."

"Again, it's the 'what would have, what could have,'" Fauci said when asked whether lives could have been spared had social distancing been implemented weeks earlier. "It's very difficult to go back and say that. I mean, obviously, you could logically say that if you had a process that was ongoing and you started mitigation earlier, you could have saved lives. Obviously, no one is going to deny that. But what goes into those kinds of decisions is complicated."

Fauci said that "obviously," if things were shut down "right from the very beginning, it may have been a little bit different."

"But there was a lot of pushback about shutting things down back then," Fauci said.

Later Sunday, Trump retweeted someone calling for Fauci to be removed.

Sorry Fake News, it’s all on tape. I banned China long before people spoke up. Thank you @OANN https://t.co/d40JQkUZg5 — Donald J. Trump (@realDonaldTrump) April 12, 2020

Speaking with MSNBC's Al Sharpton later Sunday, Fauci said that it first became clear to him in "the middle to end of January" that COVID-19 could cause a serious pandemic. Fauci said the realization came after learning that the disease could be transmitted from one person to another.

"As soon as it became clear that there was community spread, which means that it isn't just a travel-related case, that there are cases that are in the community under the radar screen, then it became clear that we were in real trouble," he said.

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White House spokesman Judd Deere pushed back Sunday on The Times' report, saying that in January and February, Trump "took bold action to protect Americans and unleash the full power of the federal government to curb the spread of the virus, expand testing capacities, and expedite vaccine development when we had no true idea the level of transmission or asymptomatic spread."

"The President remains completely focused on the health and safety of the American people and it is because of his bold leadership that we will emerge from this challenge healthy, stronger, and with a prosperous and growing economy," Deere said.

As of Saturday, the U.S. had surpassed Italy as the country with the most coronavirus deaths, with more than 20,000, according to NBC News figures. The death toll worldwide is more than 107,000, with more than 1.7 million cases confirmed, according to Johns Hopkins University.

Dr. Tom Inglesby, director of the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health, said on "Fox News Sunday" that the Times article "reinforces what we've heard along the way — which is that many people in the administration were very worried about this as early as January or February."

"That seems pretty clear now," he said. "And I'd also say that if we acted on some of those warnings earlier, we would be in a much better position in terms of diagnostics and masks and personal protective equipment and getting our hospitals ready."

New Jersey Gov. Phil Murphy, a Democrat, said on CNN that "a national postmortem" on the coronavirus response will be needed at some point.

"Please, God, I hope we do a national postmortem that's not partisan, that just asks the tough questions that were asked by the 9/11 Commission," Murphy said, adding: "We're going to need to do the same thing in our state. The woulda, shoulda, coulda deserves an important focus. Right now, again, the house is on fire. We've got to put the fire in the house out, and then we've got to begin to get back on our feet. And then, at that point, we have to look back and say, 'What could we have done differently?'"

Asked when Americans can expect the country to begin reopening, Fauci said the critical issue will be whether states and localities will be able to "identify, isolate and contact-trace" new cases in real time. Reopening parts of the country and the economy will happen on a "rolling" basis, he added.

"It is not going to be a light switch that we say, OK, it is now June, July or whatever, click, the light switch goes back on," Fauci said. "It's going to be depending where you are in the country, the nature of the outbreak that you have already experienced and the threat of an outbreak that you may not have experienced.

"I think it's going to have to be something that is not one size fits all," he added, saying the process could begin next month.

"We are hoping that, at the end of the month, we could look around and say, OK, is there any element here that we can safely and cautiously start pulling back on?" he continued. "If so, do it. If not, then just continue to hunker down. And that's what, at least for me [from the] standpoint of the public health aspect, that we look at."

On "Fox News Sunday," Inglesby said May 1 would be "too soon to reopen the country."

"No country has reopened altogether in the way that's been considered," he said. "So I think even when we do ease social distancing, it's going to need to be very careful."

On NBC's "Meet the Press," Stephen Hahn, commissioner of the Food and Drug Administration, said, "The task force, the president, the vice president, all the doctors on the task force are really looking at this from a balanced approach.

"The primary issue here is the safety and the welfare of the American people," Hahn said of reopening the country. "That has to come first."

Fauci, asked whether voters will be safe to vote as normal in November, said that he hopes so but that he "can't guarantee it."

"I believe that, if we have a good, measured way of rolling into this, steps towards normality, that we hope, by the time we get to November, that we will be able to do it in a way which is the standard way," Fauci said. "However — and I don't want to be the pessimistic person — there is always the possibility, as we get into next fall and the beginning of early winter, that we could see a rebound.

"And, hopefully, what we have gone through now and the capability that we have for much, much better testing capability, much, much better sera surveillance capability and the ability to respond with countermeasures, with drugs that work, that it will be an entirely different ballgame," he said.