WASHINGTON — President Joe Biden on Thursday plans to announce sweeping new vaccine mandates designed to ramp up pressure on the unvaccinated, putting in place additional requirements for federal employees, large employers, and health care providers that the administration said would affect around 100 million workers, more than two-thirds of the U.S. workforce.

Biden will ask the Department of Labor to issue a rule requiring all employers with 100 or more employees to ensure their workforce is fully vaccinated or produce a negative Covid test at least once a week, said a senior administration official. The requirement could carry a $14,000 fine per violation and would affect two-thirds of the country’s workforce, the official said.

Biden will also order that the vast majority of health care facilities require their staff be fully vaccinated as a condition of Medicare and Medicaid reimbursement, a move that would affect 17 million workers at 50,000 health care providers, the official said. As of July, 27 percent ofthe country’s health care workers were unvaccinated, according to a study by the Covid States Project.

The administration, which shied away from mandates early in the summer, is now embracing them, as the president Biden once billed as the “summer of freedom” ends with thousands of unvaccinated Americans dying from Covid-19 every week. Much of Biden’s wider agenda and political standing is seen as dependent on his ability to address the pandemic, with his approval numbers falling as new infections rise.

Biden will announce the measures in a speech from the White House Thursday as part of a broader plan to combat the virus.

In the remarks, Biden is also expected to announce two executive orders requiring all federal executive branch workers and employees of contractors that do business with the federal government be vaccinated, according to a person familiar with the plans. Biden had given federal workers the choice of undergoing regular testing instead of getting vaccinated, but that testing opt-out will no longer be an option.

"It’s simple: If you want to work for the federal government, you must be vaccinated. If you want to do business with the government, you must vaccinate your workforce," the senior administration official said.

To make testing more accessible, the president will announce that Walmart, Amazon, and Kroger will start selling at-home rapid tests for no profit for the next three months, resulting in a 35 percent price cut by the end of the week. Medicaid will also cover at-home tests for free for beneficiaries, and the federal government will expand a free testing program to 10,000 pharmacies.

To help address surging cases in schools that has results in hundreds of closures over the past month, an administration official said the president will call on all schools to set up regular testing and plans to make additional funding available for local school districts that have had their funding cut by state governments for implementing Covid safety measures, such as mask requirements.

The Department of Education has launched investigations into whether mask mandates in five states discriminate against students with disabilities who are at heightened risk for severe illness from Covid by preventing them from accessing in person education, the official said.

The administration will also require 30,000 Head Start teachers to be vaccinated and will call on governors to require vaccinations for teachers and school staff, the official said.

The CDC recommends testing be offered to students who have not been fully vaccinated when there is an elevated spread of the virus, and teachers and staff who have not been fully vaccinated should be screened regardless of the level of community transmission.

Biden’s Covid reset comes as the rapidly spreading delta variant threatens to stall the country’s economic rebound and derail efforts to return students to the classroom. Just weeks into the return to school tens of thousands of students and staff have had to isolate themselves following school outbreaks, and the administration attributed August’s disappointing jobs numbers to the variant as consumer confidence falls.

Biden’s approval rating for his handling of the coronavirus outbreak has steadily decreased over the summer, from 63 percent at the end of June to 53 percent this week, according to the FiveThirtyEight polling average. He’s also seen a drop in his wider approval rating, which slid 6 points since July to just 43 percent, in an NPR/PBS NewsHour/Marist poll released last week.

Entering the summer, Biden promoted his success at getting Covid cases to the lowest level since the start of the pandemic and predicted 70 percent of adults would be vaccinated by Independence Day. White House officials said they hoped Biden’s pandemic response would restore Americans’ faith in government and make it easier to sell other aspects of his domestic agenda, like an ambitious infrastructure spending package.

“America is headed into the summer dramatically different from last year’s summer: a summer of freedom, a summer of joy, a summer of get-togethers and celebrations,” Biden predicted on June 2. “An all-American summer that this country deserves after a long, long, dark winter that we’ve all endured.”

The summer was indeed different, but not in the way Biden had anticipated. States such as Florida set records for the number of patients hospitalized with Covid, as new cases across the country went well above the numbers seen last summer due to the spread of the delta variant.

But at the same time, Americans followed through on Biden’s prediction of a return to celebrations and gatherings, something that now has public health officials fearing a new wave of infections following Labor Day weekend travel and get-togethers.

Across the country, states are seeing hospitals overwhelmed with Covid patients. In Idaho, which has some of the lowest vaccination rates in the country, officials said Tuesday they were allowing health care providers to begin rationing care to make scarce resources available to patients most likely to survive because of a severe shortage of staff, beds and equipment.

There has been some improvement in the pace of vaccinations, which started increasing again in recent weeks after leveling off in July. The U.S. passed the milestone this week of having 75 percent of adults at least practically vaccinated. The biggest gains have been among young adults and teens, which White House officials have attributed to vaccine mandates by colleges and employers along with increased fears from the delta variant.

The U.S. has also started to see a downturn in the number of new cases and deaths over the past week. But public health officials have warned that could be a short-lived break, following Labor Day weekend gatherings and millions of kids going back to school this week.

Health officials are also warning of a winter surge that could coincide with particularly severe flu seasons with kids back in school, people congregating more than last winter, and mask requirements gone in most of the country.