He is due to deliver a speech setting out the administration's next steps in increasing vaccination rates around the country as officials battle the rapidly spreading Delta variant.
Meanwhile the head of the Centers for Disease Control and Prevention said 'health passes,' such as those used in Europe may have a role in helping people gather safely.
On Tuesday, Biden said mandatory vaccination was 'under consideration' for all federal workers.
Officials insist a final decision has not yet been taken but Dr Irwin Redlener, Director of the National Center for Disaster Preparedness at Columbia University, said the signs were clear.Insurance Loans Mortgage Attorney Credit Lawyer
'I think we are seeing these trial balloons going up from the White House that this is coming,' he said.
The Department of Veterans Affairs has already announced it will require frontline health care workers to be vaccinated over the course of the next two months.
White House Principal Deputy Press Secretary Karine Jeanne-Pierre said vaccination requirements could vary from department to department withing the government.
President Biden arrived in Allentown, Pennsylvania, on Wednesday where reporters asked whether he was considering mandatory vaccines for military personnel. He did not answer
Biden is due to set out his administration's next steps in getting more Americans vaccinated on Thursday, when he is expected to announce mandatory vaccinations - or a testing and mitigation regimen - for all federal staff and contractors to rein in the surging Delta variant
Biden said mandatory COVID-19 vaccines for federal workers were 'under consideration' during a visit to the Office of the Director of National Intelligence in McLean, VA
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He denied that changing official advice was causing confusion and instead said it was the unvaccinated who were to blame for rising levels of infection
'Our goal as a federal employer is to keep our employee safe and to also save lives - that is the number one goal that we have here,' she told reporters aboard Air Force One as the president traveled to Pennsylvania.
'While no decision has been finalized I will say that the attestation of vaccination for federal employees is one option under strong consideration... which means confirming vaccination status or abiding by stringent COVID-19 protocols, like mandator mask as wearing masks even in communities not with high or substantial spread, and regular testing.'
She was speaking a day after the Centers for Disease Control and Prevention recommended that fully vaccinated against COVID-19 should go back to wearing masks indoors in regions where infections were on the rise.
The moves illustrate how far the nation is from the 'summer of freedom' that Biden promised just last month.
Redlener said the 'retrograde' steps reflected how scientists were reacting to new data that showed the danger of the Delta variant.
'Predicting what is going to come next, even a month from now, is very hard,' he said.
Another possible option might be 'heath passes,' which are being used in some parts of Europe to offer proof of vaccination and allow people to gather.
In an interview with CNN, CDC Director Dr. Rochelle Walensky did not rule out the idea.
'I think some communities are doing that,' she said. ;And that may very well be a path forward.'
However, she warned they may offer a false sense of security if, as new evidence appears to show, asymptomatic, vaccinated people can transmit the Delta variant.
The Delta variant is blamed for surging numbers of COVID-19 infections in the U.S., triggering a range of new measures to halt its spread
President Biden had promised a 'summer of freedom' but the numbers keep going up
Biden was asked about