President Biden is said to be giving “strong consideration” to new requirements for federal employees to help arrest the spread of the delta variant of the coronavirus, according to NPR.

One option under consideration: verifying that federal employees are vaccinated for COVID-19 using an “attestation of vaccination,” a source familiar with the deliberations has told NPR.

Under the policy, federal employees who are not confirmed as vaccinated would be required to wear masks at all times while at work and be tested regularly for the virus, the source said, speaking on the condition of anonymity. 

Completion of the review of the policy is expected later this week.

Biden was asked himself by reporters Tuesday whether he’s considering a vaccine mandate for the federal workforce. “It’s under consideration right now,” he replied.

In a statement, Biden said he would lay out his next steps on how to get more Americans vaccinated on Thursday, noting that vaccinations are the best way to protect against the delta variant. 

“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,” he said.

The president’s statement followed revised guidance from the Centers for Disease Control and Prevention on Tuesday. The CDC reversed a position, recommending that fully vaccinated people should wear masks indoors if they’re in places with “substantial” or “high” spread of the virus.

The CDC is also now recommending universal indoor masking for all teachers, staff, students and visitors to K-12 schools, regardless of vaccination status.