Anthony S. Fauci, the nation’s top infectious-disease expert, said in interviews Sunday that former president Donald Trump should be enlisted to encourage his supporters to get a coronavirus vaccine, after recent polling showed Republican men and Trump supporters have the highest rates of vaccine hesitancy.

An NPR-PBS NewsHour-Marist poll released last week showed that nearly half of Republican men and 47 percent of those who supported Trump in the 2020 election said they would not choose to be vaccinated, even if the coronavirus vaccines were made available to them. By contrast, only 10 percent of supporters of President Biden said they would not choose to be vaccinated if offered one, the poll found.

Fauci, the director of the National Institute of Allergy and Infectious Diseases, called the poll results “so disturbing.”

“How such a large proportion of a certain group of people would not want to get vaccinated merely because of political consideration, it makes absolutely no sense,” said Fauci. “And I’ve been saying that for so long. We’ve got to dissociate political persuasion from what’s common-sense, no-brainer public health things.”

As he has for weeks, Fauci touted the effectiveness of the three coronavirus vaccines available to U.S. adults, and emphasized the history of vaccines rescuing society from infectious diseases such as smallpox, polio and measles. “What is the problem here? This is a vaccine that is going to be lifesaving for millions of people. How some groups would not want to do it for reasons that I just don’t understand,” said Fauci.

Fauci’s alarm mirrored that of other public health experts who have voiced concern about whether the United States can reach herd immunity through vaccines, which they believe could be when between 70 and 85 percent of the population is inoculated. While messaging on vaccine safety has been focused on possible hesitancy among certain racial groups, recent polling suggests the divide could be greater between political groups.

Trump, who has pushed people to give him credit for the vaccines, did tell the crowd at the Conservative Political Action Conference last month: “Everybody, go get your shot.” Earlier this month, Trump’s office revealed that the former president had received a vaccine in January before leaving the White House but did not publicize it.

However, Trump did not participate in a recent public service announcement by the Ad Council that featured all of the other living former presidents encouraging Americans to get vaccinated, an omission Fauci said was “puzzling.”

Any push by Trump “would make all the difference in the world.”

“He’s a very widely popular person among Republicans,” he added.

On Sunday, Fauci said that accelerating vaccinations and recent drops in daily cases and deaths are encouraging, but that he remained concerned about what could be a recent leveling off in the decline in new infections. “When you see a plateauing at a level of anywhere between 50,000 and 65,000 cases a day, that is absolutely no time to declare victory, because we know from previous surges we’ve had over the year that when you see that leveling off at a high level, there’s always a risk of a surge back up,” Fauci said. “And, in fact, unfortunately, that’s exactly what’s happening in Europe right now.”

Fauci said it would be “ill-advised” to ease restrictions on gatherings, and he said the decision earlier this month by Texas Gov. Greg Abbott (R) to lift a statewide mask mandate and open businesses was “risky and potentially dangerous.”

“If you look at the numbers, we’re not out of the woods yet,” Fauci said.

In his first prime-time address as president Thursday, Biden vowed that all U.S. adults would be eligible for vaccination no later than May 1, and that he was confident that friends and family members would be able to gather in small groups by July 4 to celebrate the Independence Day holiday. He also urged people to trust in the vaccines’ safety and effectiveness and encouraged people to talk to family, friends and neighbors about getting the shots when it’s their turn.

“Talk to your family, friends, your neighbors. The people you know best have gotten the vaccine. We need everyone to get vaccinated,” Biden said.