The Centers for Disease Control and Prevention’s (CDC) new guidance has thrown Congress into disarray and sparked debate over a central question: to mask or not to mask? Some lawmakers, such as Senator Tim Kaine, are gradually adjusting. On Tuesday, Kaine exited a committee hearing while wearing a mask. But an hour later, as he approached the Senate basement, he was missing his mask. He was masked again as he passed by the same location minutes later.

Different rules have created parallel universes in Congress, complicating individual decision-making. Senators are removing their masks on one side of the Capitol. On the other hand, unless speaking, masks are still required on the House floor.

With the exception of a few senators, all have disclosed that they are fully vaccinated, making it easier for senators to return to normalcy. However, while all House Democrats have been immunized, a survey found that only 95 of the 211 Republican House members have confirmed they have been immunized. The House maintains its mask mandate on the floor and in committees, unless a member is speaking. Speaker Nancy Pelosi also announced that Democrats would extend proxy voting until early July.

House Republicans are expressing displeasure with these decisions. Rep. Brian Mast was seen in the House chamber without a mask. Rep. Marjorie Taylor Greene (R-GA) also tweeted a photo of herself and three other lawmakers standing on the House floor without masks, claiming that masks were “oppressive.”

House Democratic leaders defended their decision to continue requiring masks on the chamber floor, claiming that they are simply adhering to the guidelines established by the Capitol physician. Some retaliated against GOP critics, arguing that if Republicans want to return to normalcy, they should encourage their hesitant colleagues to get immunized.

“The CDC guidelines… state unequivocally that workplaces can determine their own unique characteristics based on their conditions. And I believe we can all agree that the House floor is in a unique state, especially with Republicans admitting that only 75% of their members are vaccinated “Rep. Pete Aguilar, vice chair of the House Democratic Caucus, made the statement.

Just across the Capitol, the dynamic is different. The attending physician wrote to Senate leadership, which was shared with Senate offices last week, saying that if people were fully vaccinated, they could “resume activities that they did prior to the pandemic.”

“You can resume activities without wearing a mask or keeping 6 feet apart,” the doctor wrote in the letter, a copy of which The Hill obtained.

Unlike a letter sent to House lawmakers, this guidance makes no exception for the Senate floor, where masks are encouraged but never required. Senators have mostly stopped wearing masks, though a few Republican senators and a sizable number of Democrats have been seen wearing them around the Capitol and during votes.

Senators hinted at a return to normalcy, despite the fact that the Capitol remains closed to tours and the office buildings are still reserved for staff or planned-in-advance meetings. “It’s nice to see some smiling faces again,” said Sen. John Thune, the No. 2 Senate Republican, at a weekly leadership press conference, adding that it was “proof and evidence that vaccines work.”

Senators’ decision to wear a mask is largely ad hoc. “If I’m going into a meeting where there will be a lot of us in one smaller area, I wear a mask,” Sen. Mike Rounds said, opening his jacket pocket to show he was carrying a mask. “I’m not wearing a mask if I’m walking down the halls like this.”

After being photographed wearing a mask immediately following the new CDC guidance, Senate Majority Leader Charles Schumer has gone maskless this week. Republicans are paying attention. When asked about masks, Sen. Chuck Grassley said, “I think I took my cue from when Schumer came to the floor… without a mask.”