Sources familiar with the discussion told ABC News Chief White House Correspondent Cecilia Vega that the president is awaiting the outcome of a policy review, but that likely Thursday, he will announce that federal employees will be required to be vaccinated or else they must abide by "stringent COVID-19 protocols like mandatory mask wearing -- even in communities not with high or substantial spread -- and regular testing."
This comes one day after the Department of Veterans Affairs moved to require all of its health workers get a COVID-19 vaccine and within hours of the Centers for Disease Control and Prevention cited new science on the transmissibility of the delta variant and reversed its mask guidance.
With 2.1 million workers, the federal government is the nation's largest employer and this would be the largest vaccine mandate by a single employer.
"It's under consideration right now," Biden said of a vaccine mandate for federal workers Tuesday afternoon. "But if you're not vaccinated, you're not nearly as smart as I thought you were."
As he wrapped a visit to the Office of the Director of National Intelligence, ABC News also asked the president about Tuesday's new guidance from the CDC, recommending masks for vaccinated Americans in public, and whether it would cause confusion, but Biden continued to focus on those who remain unvaccinated.
"We have a pandemic because the unvaccinated -- and they're sowing enormous confusion," he said. "The more we learned -- the more we learn about this virus and the delta variation, the more we have to be worried, concerned."
"And the only one thing we know for sure, if those other 100 million people got vaccinated we'd be in a very different world. So get vaccinated. If you aren't, you're not nearly as smart as I thought you were," Biden continued.
Further pressing that point, the CDC late Tuesday issued a health alert to doctors on the need to increase vaccinations "to prevent surges in new infections" that could "overwhelm healthcare capacity" and increase the death toll.
Following his remarks, Biden released a statement saying the CDC decision is "another step on our journey to defeating the virus" and that he'd have more to say on Thursday when he will "lay out the next steps" to get more Americans vaccinated.
Regarding the CDC recommendation for students, Biden said it's "inconvenient," but gives them a chance to learn "with their classmates with the best available protection."
He also acknowledged concerns that as cases rise and mask guidance is reversed that the U.S. could be heading back to restrictions and closures but said in the statement, "We are not going back to that."
"In the meantime, more vaccinations and mask wearing in the areas most impacted by the delta variant will enable us to avoid the kind of lockdowns, shutdowns, school closures and disruptions we faced in 2020. Unlike 2020, we have both the scientific knowledge and the tools to prevent the spread of this disease," he said. Biden plans to wear a mask when he is in higher transmission areas, following the latest CDC guidance.
Earlier Tuesday, the CDC cited new science on the transmissibility of the delta variant and reversed its mask guidance to recommend that everyone in areas with high levels of COVID, vaccinated or not, wear a mask, as the virus continues to spread rapidly across the U.S.
"This new science is worrisome and unfortunately warrants an update to our recommendation," CDC Director Rochelle Walensky told reporters during a briefing on Tuesday afternoon.
Throughout Washington there was a quick return to mask wearing for many who had grown accustomed to being without.
Vice President Kamala Harris, meeting with Interior Secretary Deb Haaland and Native American voting rights advocates Tuesday afternoon, wore a mask indoors for the first time since May 13.
Asked about the development, Harris gave a little shrug.
"None of us like wearing masks," she said bluntly.
She noted that most people dying at this point are not vaccinated.
"People need to get vaccinated. That's the only way we're going to cut this thing off. No one likes wearing a mask. Get vaccinated. That's it," she said, hitting her hand on the table for emphasis.
ABC News' Libby Cathey, Cheyenne Haslett and Anne Flaherty contributed to this report.