But during a meeting on infrastructure, held in the Oval Office with a bipartisan group of senators earlier in the day, Mr. Biden removed his face covering. So did the lawmakers, Senator Shelley Moore Capito, Republican of West Virginia, told reporters.
In the West Wing, officials, who had been restricted from holding large in-person meetings, began removing their masks as the administration issued new guidance for anyone on the complex: People who had their last required vaccine dose at least 14 days earlier are now permitted to remove face coverings.
The news shocked some junior aides, who knew that an impromptu event was being set up in the Rose Garden, but did not know that they would soon be able to remove their face coverings. Officials who are vaccinated are still tested for the coronavirus at least once per week, and that is expected to continue, according to an administration official who was not authorized to discuss internal planning.
After so many months of avoiding one another in public and standing far apart, some officials seemed unable to avoid blurting out the first thing that came to their minds. “You’ve got a great smile,” Vice President Kamala Harris told Mr. Biden as he approached the lectern in the Rose Garden.
On Capitol Hill, where nearly all lawmakers are vaccinated and work is slowly returning to normal, the initial response appeared to break down — like nearly everything else — along somewhat more partisan lines.
“Free at last,” Senator Mitch McConnell of Kentucky, the Republican leader, said as he walked out of the Senate maskless on Thursday afternoon. A few minutes later, his Democratic counterpart, Senator Chuck Schumer of New York, exited through the same ornate corridor with a mask still tightly affixed to his face. He ignored a reporter shouting a question about when he would remove it.
Ever the club-like institution, the Senate had never agreed to put in place a formal mask mandate of the sort many other parts of the government, including the House of Representatives, did. Instead, senators relied on lawmakers following C.D.C. guidelines and sent most of their staff members home for the worst stretches of the pandemic.