“People are dying, and will die, who don’t have to die,” President Biden said on July 29, calling on unvaccinated Americans to get vaccinated against covid-19. (Video: The Washington Post)

President Biden announced Thursday that all federal employees and on-site contractors will have to be vaccinated against the coronavirus or be required to wear masks and undergo repeated testing, an order that will affect millions of workers and is designed to be a model for other employers.

The new policy, a major change in the White House strategy against covid-19, reflects a heightened concern within the West Wing about the raging delta variant, which is driving up infections and hospitalizations throughout large swaths of the country, at the same time that vaccination rates have stalled.

The administration hopes that the new directive will have a ripple effect and persuade an array of state and local governments, as well as private companies, to push their workers and customers harder to become vaccinated.

“I think you’re going to find the patience of businesses, and the patience of other people, running thin,” Biden said, his voice at times rising in exasperation. “Because the fact is, if we had a higher vaccination rate, we wouldn’t be in this position,”

He added, “If in fact you are unvaccinated, you present a problem — to yourself, to your family, and to those with whom you work. . . . You want to know how we put this virus behind us? I’ll tell you how. We need to get more people vaccinated.”

The announcement drew immediate pushback, including from federal unions. The Federal Law Enforcement Officers Association, which represents more than 26,000 officers, said requiring vaccines is an infringement on civil rights. The American Postal Workers Union also said it was opposed to requiring vaccinations for its members.

A White House spokesperson said Thursday night that U.S. Postal Service workers would not be subject to the mandate.

The need for mandates was dismissed by many at first, in part because public health officials assumed they wouldn’t be necessary once vaccines were widely available. But now that they have become the latest front in America’s culture wars and up to 30 percent of Americans are refusing to get a vaccine, many leaders are reconsidering whether tougher measures are needed.

The country is experiencing a seven-day average of nearly 70,000 new covid-19 cases a day now, after the rate fell as low as roughly 11,000 new cases daily last month. During his speech Biden made several direct appeals to the unvaccinated.

Biden, in his impassioned half-hour appeal, often divided his message between vaccinated and unvaccinated Americans, almost as though they were two separate countries. If you are not vaccinated, he pleaded, get a shot; and if you are, please be patient.

To those who are resisting immunizations, he said, “It’s an American blessing that we have vaccines for each and every American. . . . This is such a shame to squander that blessing.”

And to the vaccinated, he said, “I know it’s frustrating. I know it’s exhausting to think we’re still in this fight.” But, he added, “This is no time to be despondent or let our guard down. We just have to finish the job — with science, with facts, with the truth.”

Roughly 164 million Americans have been fully vaccinated, according The Washington Post’s vaccine tracker. About 90 million Americans haven’t had a single shot. An additional 26 million have had only one of the two required shots, and therefore aren’t fully inoculated.

The president’s directive for now affects only the civilian workforce, but he said he has asked the Defense Department to examine adding the coronavirus vaccine to the nearly two-dozen inoculations that are already required for service members. There are roughly 2 million federal employees, and close to 4 million federal contractors, giving Biden’s actions a potentially powerful impact.

Late Thursday, Pentagon spokesman Jamal Brown said that military and civilian personnel will be “asked to attest to their vaccination status.” Those unable or unwilling to take that step will have to wear masks, socially distance and undergo regular coronavirus testing, Brown said. Their travel will also be restricted.

John Kirby, a Pentagon spokesman, said that the deployment of unvaccinated troops will continue. But “they have additional guidelines to meet.”

Seeking to deploy carrots as well as sticks, Biden also said he is calling on state and local governments to offer $100 payments to everyone who gets the vaccine.

“I know that paying people to get vaccinated might sound unfair to people who got vaccinated already,” the president conceded. “But here’s the deal: If incentives can help us beat this virus, I believe we should use them. We all benefit.”

The money would come from the $350 billion fund to help states, local governments and territories that was part of the American Rescue Plan passed by Congress earlier this year.

And the president appeared open to more aggressive measures, saying it is “still a question whether the federal government can mandate the whole country” to take the vaccine.

The country appears to be at something of a pivotal point as a critical mass comes to accept that some form of vaccine requirement may be necessary. Earlier this week, California and New York said they would require government employees to either be vaccinated or face repeated testing requirements, and high-profile companies like Google and Facebook are also adopting stricter measures.

“This week has been a very important — I don’t know how you want to phrase it — breaking of the dam, tidal wave, tipping point, there are lots of ways of putting it,” said Ezekiel J. Emanuel, vice provost of the University of Pennsylvania. “There has been a consensus that we are going to have to have mandates.”

The Centers for Disease Control and Prevention this week also reversed its earlier recommendations on masking, sending out new guidance that even vaccinated Americans must wear face coverings in areas where the virus is spreading at high levels. That has prompted a new round of indoor mask mandates across the country, including in Washington.

Still, the movement against vaccines and mandates remains powerful, as some activists complain that they infringe on liberty and others embrace conspiracy theories about the coronavirus shots. Courts have so far upheld the mandates, but the clashes are likely to escalate in the fall as universities require vaccines and schools insist on masks.

In a potential sign of battles to come, Arkansas Gov. Asa Hutchinson, a Republican, announced Thursday he was calling a special session of the legislature to repeal a law that forbids public schools in the state from requiring masks. In contrast, Gov. Greg Abbott of Texas, also a Republican, issued an executive order, also Thursday, preventing local governments from issuing mandates.

In a stark visual symbol of the changing landscape, Biden himself wore a black mask as he walked up to the lectern in the East Room of the White House on Thursday, the first time in weeks he had been spotted wearing one.

After Biden removed the mask for his speech, he said that “a significant part of the country wouldn’t have to take one of these off” because the federal guidance recommends masks only in places where there is high transmission. He noted that he did not have to wear a face covering during his trip Wednesday to Pennsylvania — and would also not need one in Wilmington, Del., where he spends many of his weekends.

“They don’t need a mask when the majority, the vast majority, of people got vaccinated,” Biden said.

The president also tried to address head-on some of the reasons Americans haven’t opted to get their shots. He said that the science behind the vaccines had been under development for “decades,” an appeal to those who worry that the shots were developed in haste and might not be safe.

And he made his strongest pitch to date that the shots should not be politicized.

“The vaccine was developed and authorized under a Republican administration,” Biden said. “It’s been distributed and administered under a Democratic administration.”

He added, “This is not about red states and blue states — it’s about life and death.”

A major remaining question is when and whether service members will have to get vaccinated. Military leaders have wanted to wait until the Food and Drug Administration gives final approval for the shots, rather than the current emergency authorization. Some commands have started preparing for mandatory inoculations, according to the Army Times.

The Defense Department has nearly 1.4 million people on active duty, and roughly 69 percent of them have received at least one shot.

Pushing back against misinformation about the vaccine, Biden credited Republicans who have called on Americans to get vaccinated, including Senate Minority Leader Mitch McConnell (Ky.) and Alabama Gov. Kay Ivey.

McConnell has used some of his campaign funds to pay for an ad urging vaccinations. And Ivey recently bluntly said that “it’s time to start blaming the unvaccinated folks” for the recent increase in cases.

“This is not about red states and blue states. It’s literally about life and death. It’s about life and death,” the president said.

The White House shift on pushing federal workers to be vaccinated comes days after the Department of Veterans Affairs mandated that about 100,000 of its employees be vaccinated. Denis McDonough, the secretary of veterans affairs and a former White House chief of staff to President Barack Obama, limited his order to those who interact with patients.

Public health experts have been long calling for the Biden administration to use stronger methods such as mandates to push recalcitrant Americans to get shots.

“This is a course correction,” said J. Stephen Morrison, who directs the Global Health Policy Center at the Center for Strategic and International Studies. “This is a very big change. . . . It is overdue.”

Morrison added, “They’re trying to regain momentum, and they’re trying to reassert the federal hand guiding things rather than taking the kind of approach up to now that they’ve taken, which is more sitting back and allowing others to lead,” Morrison said. “They’re beginning to recognize that there’s a price for that: It has an appearance of a kind of abdication.”

Biden acknowledged he faces a balancing act, pushing reluctant Americans to get a vaccine while urging those who got their shots to be patient just a little longer.

“I understand that many of you in the majority are frustrated with the consequences of the failure of the minority to get vaccinated,” Biden said. “But I want you to know I’m going to continue to do everything I can to encourage the unvaccinated to get vaccinated.”

Dan Lamothe, Eli Rosenberg and Jacob Bogage contributed to this report.