Masks have become the norm inside the House of Representatives, where some politicians embrace the novel coronavirus precaution with colorful odes to their home districts. But there are holdouts: a small group of Republican representatives who have consistently declined to wear face coverings in Congress.

Now, as nine states hit record highs for infections, House Speaker Nancy Pelosi (D-Calif.) is tightening the rules. Late Tuesday, she asked committee chairs to require masks at all hearings — and authorized the sergeant at arms to bar anyone who refuses to cover their face, according to a senior aide familiar with the request.

“This requirement will be enforced by the Sergeant at Arms and non-compliant Members will be denied entry,” the senior aide said in an email to The Washington Post. “Ultimately, Chairs will have the option of not recognizing Members in committee proceedings that fail to comply with the mask requirement.”

The change could set off new political tensions around face coverings, which have become politicized as President Trump consistently declines to wear masks in public and mocks his political opponents for doing so. In the Illinois House last month, a GOP representative was thrown out for refusing to mask up — a preview of what could happen if prominent holdouts push the envelope in hearings this week.

As Wednesday’s House Judiciary Committee hearing on police reform kicked off, some of the holdouts, including the panel’s ranking Republican, Rep. Jim Jordan (Ohio), could be seen wearing face masks inside the hearing room.

Rep. Jerrold Nadler (D-N.Y.), the panel’s chairman, began the meeting by making note of the new rules and warning members that those who refuse to wear masks will be asked to participate remotely.

“After this markup is over, we will go home to our loved ones,” Nadler said. “Wearing a mask helps protect them from serious illness as well. As chairman, I have a duty and responsibility to maintain order and decorum in our proceedings, which includes making sure that we conduct our business in a safe manner in light of the attending physician’s new guidance. I therefore fully expect all members on both sides of the aisle to wear a mask at all times that you are not speaking.”

“If, for whatever reason, you are not willing to wear a mask, the House rules provide a way to participate remotely from your office without being physically present in this room,” he added.

Tuesday’s change comes after Pelosi requested new official guidelines from Brian P. Monahan, the attending physician of Congress, based on the emerging scientific consensus that masks are key to slowing the spread of coronavirus. Monahan’s updated guidance, which he issued Tuesday, requires face masks in the House for anyone meeting “in a limited enclosed space, such as a committee hearing room, for greater than 15 minutes.”

That’s the rule Pelosi has asked committee chairs to enforce. For now, wearing masks on the House floor or in most other areas of the Capitol are still only “strongly recommended” under Monahan’s guidelines.

The new rules are academic for most politicians in both parties, who have largely embraced masks in the House since the early days of the pandemic. But Jordan and a handful of other Republicans have resisted face coverings.

Jordan, who was upbraided by Democrats for not wearing a mask during an April hearing, has argued that maintaining six feet of distance is precaution enough.

Others have cast their defiance in biblical terms.

“Can you smell through that mask? Then you’re not stopping any sort of a virus,” Rep. Clay Higgins (R-La.) told CNN last month, an argument not supported by science about the disease’s spread. “It’s part of the dehumanization of the children of God. You’re participating in it by wearing a mask.”

Rep. Ted Yoho (R-Fla.), meanwhile, also told CNN “there’s just no need” to wear a mask in the House because he believes in “herd immunity.” That concept is far from proved, scientists say, as it’s unclear how long covid-19 survivors have immunity.

One GOP congressman who declined to wear a mask at the Capitol has contracted the disease. On Monday, Rep. Tom Rice (R-S.C.) announced he had tested positive for the coronavirus, after appearing with an uncovered face on the House floor two weeks earlier.

Under Monahan’s new guidelines, lawmakers will be offered a mask at the committee door. If they don’t want to wear it, they’ll have the option to work remotely instead.

“Members always have the option to participate in committee proceedings virtually, including from their Washington, D.C., offices or their districts,” the senior aide said.