By Kaitlan Collins and Kevin Liptak, CNN

Updated 11:01 AM ET, Thu September 9, 2021

(CNN)President Joe Biden on Thursday will impose more stringent vaccine rules on federal workers by signing an executive order requiring all government employees be vaccinated against Covid-19, with no option of being regularly tested to opt out, according to a source familiar with the plans.

During a major speech meant to lay out a new approach to combating the coronavirus, the President will also sign an executive order directing the same standard be extended to employees of contractors who do business with the federal government. The Department of Defense, the Department of Veterans Affairs, Indian Health Service and National Institutes of Health will also complete their previously announced vaccination requirements, which the White House estimates covers 2.5 million workers.

The new announcements move beyond what Biden announced earlier this summer, when he required federal workers be vaccinated but allowed for those who opted out to be subject to stringent mitigation measures. The White House has said the federal government should act as a model for other businesses in their own vaccine mandates, and has praised large companies that require employees to be vaccinated.

Biden on Thursday also plans to announce a major expansion to free testing, a step public health officials have said is critical to containing the virus, particularly as children return to school and some workers return to offices.

And he will address the confusion over booster shots, though will not make any new announcements on when additional doses will be authorized for Americans.

The six-pronged plan Biden is set to unveil was finalized by the President and members of his public health team on Wednesday afternoon. He received a briefing in the Oval Office from his Covid-19 response team on the anticipated new steps.

A White House official said the six pillars of Biden's plan include: vaccinating the unvaccinated; further protecting the vaccinated through booster shots; keeping schools open; increasing testing and requiring masks; protecting the economic recovery; and improving care for those with Covid-19.

Officials said they hope the new approach will provide Americans a clearer view of how the pandemic will end after 18 months of Covid-dampened life. The White House has watched as the President's approval ratings on Covid have slipped, and feel part of the problem is the backward motion felt this summer: a spike in cases led to a return to masks and continued working from home.

An ABC News/Washington Post poll conducted at the end of August found 52% of respondents approve of how Biden is handling the pandemic, a 10-point drop from June. Still, more respondents said they approved of his handling of Covid than disapproved.

At the same time, Biden's overall approval has slipped into negative territory amid a chaotic withdrawal from Afghanistan and the Delta variant's drag on the economic recovery. The President's aides view combating the pandemic as the single most important issue of his presidency, and the one that will determine his political fate.

As American students return to classrooms, battles over masks and vaccine requirements for older children have erupted in school districts around the country. Health officials say they expect vaccines to be authorized for children under 12 in the next several months, but parents have become frustrated at the pace with which the process is unfolding.

Biden has identified schools as a key area of focus, given the broader effect that having children in classrooms has on the economy, particularly for women.

While Biden has encouraged businesses to require vaccines for workers, officials said they believe there is more the private sector can do to encourage people to get the shot. That includes requiring proof of vaccination at restaurants, bars and other venues. Administration officials have been working over the past few weeks to determine ways the government could make it easier for businesses to apply those requirements.

The White House has repeatedly said there won't be a federally mandated vaccine passport, but has been pushing other ways to increase vaccination rates.

At the same time, the administration is preparing to roll out booster shots for Americans who have already received vaccines, though the date at which the third shots will begin has been unclear.

The Biden administration had initially said last month that a third dose of the Covid-19 vaccine would be made available for adults on September 20. But top health officials warned the White House they may need more time to review all the necessary data before they can recommend booster shots. The US Food and Drug Administration is set to meet September 17 to discuss Covid-19 booster shots.