President Joe Biden lashed out today at the governor of Texas and others who have relaxed COVID-19 restrictions, describing their actions as “Neanderthal thinking” and insisting that it was a “big mistake” for people to stop wearing masks.

The president, who has urged Americans to remain vigilant in the fight against the coronavirus, said it was critical for public officials to follow the guidance of medical doctors and public health officials as the U.S. vaccination campaign progresses.

“The last thing we need is Neanderthal thinking that in the meantime, everything’s fine, take off your mask and forget it,” Biden told reporters at the White House. “It’s critical, critical, critical, critical that they follow the science. Wash your hands, hot water. Do it frequently, wear a mask, and stay socially distanced. And I know you all know that. I wish the heck some of our elected officials knew it.”

Earlier in the day, the White House press secretary, Jennifer Psaki, called on Texans and others to follow the guidance of the country’s top medical officials, who have warned mayors and governors not to recklessly abandon restrictions.

“This entire country has paid the price for political leaders who ignored the science when it comes to the pandemic,” Psaki said.

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, warned governors and mayors again today not to lift COVID-19 restrictions prematurely.

Her latest warning, the third in less than a week, came after officials in several states, including Texas and Mississippi, announced Tuesday that they are easing rules like mask mandates and capacity limits in businesses.

“Now is not the time to release all restrictions,” Walensky said at the White House briefing.

She said the United States is at a pivotal moment when it could either quell the spread of the coronavirus through precautions and vaccinations or stoke a new surge of infections.

“So much can turn on the next few weeks,” she said.

Andy Slavitt, a senior White House adviser, said health officials in every state agree that “now is the wrong time to lift the mask mandate.”

New cases, deaths and hospitalizations have been decreasing over the past week, according to a New York Times database. Compared with two weeks ago, cases were down 19%, and hospitalizations were down 29%. Deaths were down 9%. As of Tuesday, the CDC estimated that 15% of the population had received at least one dose of a virus vaccine, while nearly 8% had received both doses.

Biden said Tuesday that the nation was expected to have enough doses of vaccine available by the end of May to inoculate the whole adult population. He acknowledged it would take longer to get everyone vaccinated.

With new virus variants spreading, Walensky urged people to wear masks, to avoid crowds and travel, and to “do the right thing to protect their own health,” regardless of what their state officials dictate.

“Fatigue is winning, and the exact measures we’ve taken to stop the pandemic are now too often being flagrantly ignored,” she said.

The World Health Organization issued its own warning Monday against easing virus restrictions too soon, particularly with the circulation of new variants.

The CDC has issued detailed guidance about reopening schools and workplaces. Walensky is most concerned about lifting mask mandates and fully reopening businesses without regard to the need for social distancing, according to one federal official familiar with her thinking.

While many states have eased some restrictions in recent weeks, Gov. Greg Abbott of Texas, a Republican, made the most expansive move.

Not all Texas businesses are on board. Even as it filed for bankruptcy today, a Texas-based movie theater chain, Alamo Drafthouse, pushed back against the relaxation, saying in a message to patrons that masks and social distancing would still be required at its theaters across the state.

Gov. Tate Reeves of Mississippi, another Republican, lifted his state’s mask order Tuesday, although he said he still recommended that people wear them and practice social distancing.

Democrats are slowly easing restrictions now as well. Gov. Gretchen Whitmer of Michigan said her state would relax limits on nursing homes and allow restaurants, shops and other businesses to accept more customers starting Friday. Gov. John Bel Edwards of Louisiana said that bars in his state could reopen and live music could resume indoors, though the state’s mask mandate would continue. And in San Francisco, Mayor London Breed said indoor dining, museums and movie theaters will be allowed to reopen today at limited capacity.