Mr. Trump previewed the new set of federal guidelines in his letter as the death toll from the virus in the United States passed 1,000, and in hot spots like New York, 100 people had died because of the virus in one day. Gov. Andrew M. Cuomo of New York said on Thursday that the worst days and weeks of the crisis were still ahead.

But Mr. Trump, in his letter, said the goal of the new rules was to look toward the day when Americans could “resume their normal economic, social and religious lives.”

Earlier in the week, he said he wanted to reopen the country for business by Easter, on April 12, despite widespread warnings from health officials that the worst effects of the virus were still weeks away and prematurely lifting social distancing guidelines would result in unnecessary deaths.

At the time, Dr. Anthony S. Fauci, a leading health expert on the administration’s coronavirus task force, said the additional testing now available gave the administration some “flexibility in different areas” to do so.

“People might get the misinterpretation you’re just going to lift everything up,” Dr. Fauci said, explaining Mr. Trump’s impatience to jump-start the economy and tell Americans they could resume everyday life. “That’s not going to happen,” Dr. Fauci said. “It’s going to be looking at the data” in regions of the country where there was not an obvious outbreak of the virus.

As a practical matter, however, Mr. Trump does not have the power to decide whether the country can reopen. He can issue federal guidelines, but the decision of whether to return to business as usual is up to each state.