WASHINGTON — Vice President Mike Pence was photographed on Thursday wearing a mask while visiting a General Motors plant in Indiana in what appeared to be a tacit acknowledgment of the criticism he has received for traveling the country without one.
Mr. Pence drew intense criticism for flouting the guidelines of the Mayo Clinic, which asks all visitors to its campus in Minnesota to wear masks, during a stop there this week.
It was not the first time he has refused to don a mask since resuming a heavy travel schedule representing the administration at graduations, hospitals and factories across the country. But because he appeared to be defying rules put in place by one of the country’s most renowned medical facilities, it seemed to strike a nerve.
At the time, Mr. Pence explained that because he was tested regularly for the coronavirus, he was not at risk of contributing to asymptomatic spread and therefore did not need to wear a mask — an argument that experts immediately dismissed.
He did not address the fact that he appeared to have ignored the Mayo Clinic’s own guidelines. After his visit, the clinic posted on Twitter that it had “informed @VP of the masking policy prior to his arrival today.” The clinic then deleted the tweet, with no explanation.
But in his first public outing since then, Mr. Pence seemed to accede to public pressure by covering his face, a rare moment of backing down from a position on the part of an administration whose philosophy is often to double down in response to criticism.
Administration officials said that Mr. Pence wore the mask in deference to G.M.’s policy at the plant he was visiting. They also said Mr. Pence was never informed of the Mayo Clinic’s policy, and indicated Mr. Pence would continue to appear without a mask at other events. Karen Pence, the second lady, also said in a television interview on Fox News on Thursday that her husband had not been made aware of the mask policy.
“Mayo Clinic shared the masking policy with the vice president’s office,” said a spokeswoman for the clinic, Ginger Plumbo.
The episode incited major blowback, both for Mr. Pence and for the medical center. Former patients of the Mayo Clinic said they were livid at the exception apparently made for the vice president.
Kenneth Rinzler, a lawyer based in Washington, said he underwent open-heart surgery at the Mayo Clinic in 2010 and described himself as “eternally grateful” to the team of medical experts there.
But he wrote to the institution this week, saying he was “beyond shocked and completely heartbroken to have just watched Vice President Mike Pence walk around inside one of the buildings, and in particular visit a group of people apparently donating blood, without wearing a mask and violating every basic tenet of social distancing.”
Susie Watson of Ellison Bay, Wis., who said she spent four months at the Mayo Clinic in 2018 and 2019 when her husband underwent a bone marrow transplant there, said she also wrote to the institution this week in alarm.
“Although we appreciate your email Covid-19 updates, we were very upset to see that Mike Pence visited the campus and did not wear a mask,” she wrote in an email she also shared with The New York Times. “We think it is fair to ask why you didn’t insist that he wear one. It really makes us wonder about your judgment.”
President Trump has also expressed distaste for the look of a mask and has said he does not plan to wear one himself. He is expected to travel to Arizona next week to tour a Honeywell plant, and he has said that he intends to visit the critical battleground state of Ohio soon, too.
It remains to be seen whether Mr. Trump will concede to covering his face on trips away from the White House.
Mr. Pence was visiting a General Motors plant in his home state that had been converted into a ventilator production site. Last month, Mr. Trump used the Defense Production Act to force General Motors to step up efforts to manufacture ventilators.
“It’s amazing to think this floor was empty about a month ago,” Mr. Pence said. “It was a partnership to meet a vital need for Americans struggling in the midst of the coronavirus epidemic.”