A source familiar with the White House’s plans told Fox News that the mandate would extend to all federal workers and to millions of contractors that do work with the federal government, the nation's largest employer.
The executive order, the source told Fox News, builds on the president's announcement in July to strengthen safety requirements for unvaccinated federal workers.
The order will "take those actions a step further and require all federal executive branch workers to be vaccinated."
The mandate will also extended to employees of contractors that do business with the federal government.
Under the new order, the Department of Defense, the Department of Veterans Affairs, the Indian Health Service, and the National Institute of Health are expected to complete the implementation of their previously announced vaccination requirements that cover 2.5 million people.
The U.S. Department of Veterans Affairs, in July, became the first agency in the federal government to announce that it will require patient-facing employees to be vaccinated against COVID-19.
Despite some concern over vaccine mandates, the Justice Department Office of Legal Counsel determined over the summer that federal law does not prohibit public agencies and private businesses from requiring COVID-19 vaccines that are under emergency use authorization (EUA).
The opinion notes that some have questioned whether such entities can lawfully impose such requirements.
In the opinion, the DOJ Office of Legal Counsel says the law concerning emergency use authorizations "does not prohibit public or private entities from imposing vaccine requirements, even when the only vaccines available are those authorized under EUAs."
The Pfizer/BioNTech COVID-19 vaccine was fully approved by the Food and Drug Administration in August.
According to the CDC, more than 177.1 million Americans have been fully vaccinated.