The House of Representatives will once again require all lawmakers and staff members to wear masks inside, a sharp reversal of policy as growing fears about the Delta variant reach the doorstep of Congress. Senators will be encouraged to mask up, too, but are not required to do so.
In a memo late Tuesday night, Dr. Brian P. Monahan, Congress’s top doctor, said he was recommending the change based on new C.D.C. guidance and the nature of the Capitol, where thousands of people traveling from across the country mix each week. Speaker Nancy Pelosi made the change official on the House floor Wednesday morning.
“For the Congress, representing a collection of individuals traveling weekly from various risk areas (both high and low rates of disease transmission), all individuals should wear a well-fitted, medical-grade filtration mask (for example an ear loop surgical mask or a KN95 mask) when they are in an interior space,” Dr. Monahan wrote to House officials.
In a letter to top Senate leaders, Dr. Monahan dispensed the same advice but stopped short of recommending a mask mandate. The Senate is a smaller body, and for much of the pandemic, its members wore masks voluntarily. Most Senators are vaccinated.
The House triumphantly dropped its longtime mask requirement six weeks ago in a show of optimism that the grip of the pandemic was loosening.
Since then, at least one House lawmaker and an aide to Speaker Nancy Pelosi have tested positive for the coronavirus after being fully vaccinated. Others on Capitol Hill have gone into voluntary quarantine after exposure to individuals who were sick with Covid-19, and on Wednesday, the Senate Homeland Security Committee called off a business meeting after staff members tested positive for the virus, a committee aide said. At the same time, new cases have skyrocketed across the country.
Like broader mask guidance from the C.D.C. and aggressive interventions being considered by President Biden to increase the nation’s vaccination rate, the new mask mandate in the House is likely to test the patience of a weary public and the opposition Republican Party, which is eager to accuse Democrats of undermining confidence in vaccines and jeopardizing the health of the recovering economy. Republicans in the House immediately protested and raised the prospect that they may refuse to comply.
“Make no mistake — The threat of bringing masks back is not a decision based on science, but a decision conjured up by liberal government officials who want to continue to live in a perpetual pandemic state,” Representative Kevin McCarthy, Republican of California and the minority leader, wrote on Twitter.
House rules say that any lawmaker who does not wear a mask in specified spaces in the Capitol complex can be fined $500 or more. Several Republicans were fined earlier this year for that reason. But it is unclear what Ms. Pelosi and other House leaders would do if many Republican members refuse to go along.
Signs of such resistance were seen on Wednesday morning minutes after Ms. Pelosi announced the updated rules. When a staff member designated to work on the House floor handed a mask to Representative Lauren Boebert, Republican of Colorado, she tossed it back at the person, according to another aide who witnessed the exchange and requested anonymity to describe it.
Asked about Mr. McCarthy’s comments on Wednesday, Ms. Pelosi did little to hide her scorn. “He’s such a moron,” Ms. Pelosi was heard to say by reporters.
Ms. Pelosi’s spokesman later said he could not verify her precise words, but that the speaker indeed felt that Mr. McCarthy’s position on the issue “is moronic.”
Senate Republicans have taken a more conciliatory tack, with their top leaders pleading with conservatives who have refused vaccination to get inoculated. For instance, Senator Mitch McConnell of Kentucky, the minority leader, plans to begin using tens of thousands of dollars in campaign funds to run radio ads in his home state promoting the coronavirus vaccines as a “modern medical miracle” and urging his constituents to accept them.
“If you haven’t been vaccinated, do the right thing for you — for your family — and get vaccinated right now,” said Mr. McConnell, who recounts his own fight with polio in the ad. “I’m Mitch McConnell and I approved this message.”