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.
“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, and others on Capitol Hill have gone into voluntary quarantine after exposure to individuals who were sick with Covid-19. 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. Democrats have been far more compliant in the past, and many have begun voluntarily wearing masks again in recent days.