President Joe Biden speaks during a visit to the Lehigh Valley operations facility for Mack Trucks in Macungie, Pa., Wednesday, July 28, 2021. Credit: Susan Walsh / AP

President Joe Biden promised a “summer of joy” on July 4 as he declared America’s independence from COVID-19. Three weeks later that sense of victory is evaporating in the face of a resurgent pandemic.

The U.S. now faces a surge in cases fueled by vaccine holdouts and the highly transmissible delta variant, prompting the federal government and companies on Tuesday to weigh mandatory vaccinations of workers and a return to widespread mask wearing.

That reversal of fortune could bring back restrictions many Americans had hoped were gone for good — a bitter setback for Biden, who has counted on defeating the pandemic as a cornerstone of the nation’s economic recovery.

As the seven-day rolling average of new infections approached 52,000 on Tuesday, more than four times the level just three weeks ago, the Centers for Disease Control and Prevention issued new guidance recommending Americans resume wearing masks in indoor public places in many parts of the country — regardless of whether they’re vaccinated.

Just two months ago, the agency said vaccinated Americans could safely remove their masks everywhere.

The rapidly rising case count is prompting concern about the safety of schools, which are poised to begin reopening for the fall in less than a month, and whether the economy will suffer another blow should Americans resume social distancing practices.

Virus fears could keep Americans away from restaurants, hotels and bars, especially in areas with high transmission, and cause them to reconsider reporting to their jobs or traveling.

The apprehension was evident on Tuesday at the White House. Press Secretary Jen Psaki spent much of her daily briefing jousting with reporters over the new CDC guidance.

Since May, virtually all White House staff and reporters at the complex had gone without face coverings. But on Tuesday, even before the CDC formally announced its new recommendations, a handful of reporters and photographers donned masks at Psaki’s briefing.

Vice President Kamala Harris put one on during a meeting with Native American leaders, and reporters accompanying her were abruptly instructed to wear masks by press aides, who said the level of virus transmission in Washington had been upgraded by the CDC to “substantial.”

At 5 p.m., White House staff received an email directing them to wear masks while indoors at the White House even if they’re fully vaccinated. The White House Correspondents’ Association sent a similar message to the hundreds of journalists credentialed to be in the complex.

Staff and journalists quickly followed suit, digging masks out of bags and desk drawers.

And Congress’ doctor on Tuesday night reimposed a mask-wearing requirement for lawmakers and all others while they are on the House floor, and in hallways and offices.

After months of resisting vaccine mandates, Biden told reporters earlier Tuesday that he was considering forcing federal employees to get shots. While there have been so-called breakthrough cases among the vaccinated, Biden said the delta variant is primarily circulating among those who aren’t inoculated.

“If you’re not vaccinated, you’re not nearly as smart as I thought you were,” Biden said during a visit Tuesday to the headquarters of the Director of National Intelligence in Virginia.

Some major employers are implementing similar policies. The Washington Post announced Tuesday it would require employees to show proof of vaccination, joining the ranks of companies mandating workers get their shots. Ford Motor Co. reinstated masking requirements for workers at facilities in Missouri and Florida, after General Motors Co. did the same at a Missouri factory.

The president faces significant political risks if rising case levels once again disrupt everyday life in the U.S. He has touted progress against the virus as his most significant achievement and Americans have given him high marks for his handling of the pandemic thus far.

Almost two-thirds of Americans approved of his approach to the virus, according to a CBS News/YouGov poll released last week.

The CDC’s reversal on masks could make it more difficult to convince Americans to adhere to the new policy, according to Leana Wen, a former Baltimore health commissioner.

“The CDC made a critical mistake back in May. By issuing guidance that led to the end of indoor mask mandates prematurely, they gave the impression that the pandemic was over. It’s very hard to walk this back,” she said.

But Peter Hotez of the Baylor College of Medicine says he believes the CDC made the correct decision in easing masking rules in May and again on Tuesday, given how high viral loads are for people with the delta variant.

“They’re following the evidence, following the science,” he said. “The problem is it’s not a 30-second Unicef commercial, it takes nuance and time to explain” why the policy reversal makes sense.

Biden missed his July 4 target of 70 percent of U.S. adults receiving at least one dose of a COVID-19 vaccine, and the holdouts — particularly in parts of the country that are heavily Republican, such as the Deep South — have left the country vulnerable.

More than two weeks past that deadline, 69 percent of adults have had at least one inoculation, according to the CDC.

Republicans, many of whom have only recently begun to urge their constituents to get vaccinated, have indicated they don’t plan to offer Biden help in getting them to follow the CDC’s suddenly stricter mask guidance.

Former President Donald Trump, in a statement on Tuesday night, belittled the new concerns: “We won’t go back. We won’t mask our children.”

And Sen. Ted Cruz, R-Texas, said, “today’s decision, sadly, was driven by politics, not science. Let me be clear: There should be no more Covid mandates, no mask mandates, no vaccine mandates, no vaccine passports, no lockdowns, and no school closures. Enough is enough.”

Delta’s spread has touched all corners of the country — from Cruz’s home state, which posted its biggest daily jump in new infections in five months, to New York and Los Angeles, which have joined rural states among places where the new mask guidance applies.

But the White House has some reason to hope that the latest surge will not lead to the type of widespread turmoil and death that occurred last year.

The U.K. recently went through a spike in infections driven by the delta variant, despite having fully vaccinated 56 percent of its population, according to the Bloomberg Vaccine Tracker.

Cases there topped 50,000 a day, close to the level of the country’s winter surge. But unlike the winter peak, there has been little corresponding rise in hospitalizations or deaths, a sign that the wide use of vaccines has prevented infections from becoming severe.

Yet in the U.S., where case counts are following a similar trajectory, the outcome is less certain. Parts of the country, in particular the East and West Coasts, have vaccination levels in line with the U.K. But in the central and southern parts of the U.S., the share of people getting shots has lagged badly and hospitalization rates are rising.

In Missouri and Arkansas, two of the states with the worst ongoing outbreaks, hospitalizations are at levels not seen since January. In younger age groups, such as those ages 30-59, new hospitalizations have already passed the U.S. winter peak and continue to rise.

Story by Jordan Fabian and Jennifer Epstein, Bloomberg News