Biden is traveling to Pennsylvania to promote U.S. manufacturing, but the Delta surge may draw the spotlight.

President Biden is set to travel on Wednesday to Lehigh Valley, Pa., to bolster support for his infrastructure package as bipartisan negotiations near a make-or-break point.

But a backslide in the country’s progress toward ending the coronavirus pandemic threatened to overshadow the trip, the president’s sixth visit to the critical swing state since taking office. On Tuesday, the Centers for Disease Control and Prevention called for universal masking in schools and told vaccinated Americans that they should begin wearing masks again in the many counties in the country where the virus is surging.

Speaking and touring a Lehigh Valley plant that produces Mack Trucks, Mr. Biden was expected to underscore the importance of American manufacturing and unveil a new proposal that seeks to support domestic production by increasing the amount of U.S.-made products purchased by the federal government.

The federal government procures about $600 billion of goods a year, including everything from helicopter blades to office furniture, according to the Office of Management and Budget. Mr. Biden was expected to announce on Wednesday that he was changing the Buy American rules related to purchases made with taxpayer dollars. The plan is to increase the percentage of component parts that need to be manufactured domestically from 55 percent to 60 percent, with a graduated increase to 75 percent.

“This is all part of an effort to lift up and talk about his buy-American agenda as well as the infrastructure package,” Jen Psaki, the White House press secretary, said on Tuesday in a preview of his trip.

But Mr. Biden’s efforts to promote the economy and his infrastructure plan may yield the spotlight to the concerning new data about the spread of the highly infectious Delta variant, and the possibility of variants to come. Anxiety about the pandemic has begun to rise again, and Mr. Biden announced on Tuesday that, later in the week, he would lay out the administration’s “next steps” in getting more Americans vaccinated.

On Tuesday afternoon, the White House also instructed its staff to mask up again, in order to comply with new C.D.C. guidance. The return to masking in the West Wing came just over two months after Mr. Biden and senior officials shed their face masks, in the biggest sign of a triumphant return toward normalcy since he took office.

Mr. Biden’s trip to Pennsylvania was to be his first outing since the new guidelines were introduced late Tuesday, and he was expected to travel while wearing a mask, an image reminiscent of the early days of his presidency, when the coronavirus was raging.

Officials tried to play down the whiplash Americans might feel after being told that despite previous guidance, they should keep masks on indoors, even if they are fully vaccinated.

“What the American people should feel confident in is that we are going to continue to be guided by science, look at public health data in order to provide new guidance, if it’s needed, to save lives, to protect the American people,” Ms. Psaki said.