Biden returned to the theme later in the piece, writing, “Instead of once again seeking to divide us, Trump should be working to get Americans the same necessary protections he has gotten for himself.”

Last week, Trump said that testing is not necessary to safely end virus-related restrictions to life and work in the country, dismissing the advice of health experts, scientists and even some Republican allies.

He has also focused on the optics, noting that more testing would probably lead to increases in the official count of infected Americans. “In a way, by doing all of this testing we make ourselves look bad,” Trump said last week.

The president receives a daily test for the virus, as do the top aides who come in regular contact with him. Two White House aides recently tested positive for the virus, which Trump has pointed to as evidence that testing is not worthwhile.

“This is why the whole concept of tests aren’t necessarily great,” Trump said Friday. “The tests are perfect, but something can happen between the test where it’s good and then something happens and all of a sudden — she [the aide] was tested very recently and tested negative and today I guess for some reason she tested positive.”

In a statement, White House spokesman Judd P. Deere defended that administration’s testing response. “The United States has done more than double the number of tests of any country in the world,” he said. “We are the global leader in testing capacity and continue to work with governors to ensure they have enough capacity for a safe, responsible reopen.”

About 300,000 tests are being conducted each day throughout the country. Researchers at Harvard University have said the United States would need to conduct about 5 million tests a day by June — and 20 million a day by July — to safely return to normal life.

Sean Sullivan and Josh Dawsey contributed to this report.