WASHINGTON — As he confronts the most serious crisis of his tenure, President Trump has been assertive in closing borders to many outsiders, one of his favorite policies. But within the United States, as the coronavirus spreads from one community to another, he has been more follower than leader.

While he presents himself as the nation’s commanding figure, Mr. Trump has essentially become a bystander as school superintendents, sports commissioners, college presidents, governors and business owners across the country take it upon themselves to shut down much of American life without clear guidance from the president.

For weeks, he resisted telling Americans to cancel or stay away from large gatherings, reluctant even on Thursday to call off his own campaign rallies even as he grudgingly acknowledged he would probably have to. Instead, it fell to Dr. Anthony S. Fauci, the government’s most famous scientist, to say publicly what the president would not, leading the nation’s basketball, hockey, soccer and baseball leagues in just 24 hours to suspend play and call off tournaments.

Mayors and county executives, hospital executives and factory owners received no further direction from the president as he talked about the virus in the Oval Office on Thursday than they did during his prime-time address to the nation the night before. Beyond travel limits and wash-your-hands reminders, Mr. Trump has left it to others to set the course in combating the pandemic and has indicated he was in no rush to take further action.

“If I need to do something, I’ll do it,” the president told reporters on Thursday. “I have the right to do a lot of things that people don’t even know about.” But he again emphasized that the crisis was not as bad as many imagine. “Compared to other places, we are in really good shape,” he said, “and we want to keep it that way.”

By contrast, Leo Varadkar, the visiting prime minister of Ireland sitting next to him, said that as of Friday, his country was closing all schools and banning indoor gatherings of more than 100 people and outdoor gatherings of more than 500 — the kind of measures that some American states and cities are taking on their own rather than wait for the president.

Mr. Trump had no hesitance to kibbitz from the side before he became president, assailing President Barack Obama for not doing enough to stop Ebola, for instance. But his own White House has separated into camps of those who think the administration needs to be doing more and those who share — and reinforce — Mr. Trump’s own view that the news media is overreacting to and creating a panic around the coronavirus.

After feeling besieged by enemies for three years, Mr. Trump and some of his advisers view so many issues through the lens of political warfare — assuming that criticism is all about point scoring — that it has become hard to see what is real and what is not, according to people around the president. Even when others with Mr. Trump’s best interests at heart disagree, they find it hard to penetrate what they see as the bubble around him.

Thomas P. Bossert, a former homeland security adviser to Mr. Trump, has tried repeatedly in recent days to be patched through to the president or Vice President Mike Pence to warn them just how dire the coronavirus pandemic really is, only to be blocked by White House officials, according to two people familiar with the events. It left him to try to get the president’s — and the public’s — attention through newspaper op-ed articles, television appearances and Twitter messages like the one that panned Mr. Trump’s Europe travel ban as “poor use of time & energy.”

Mr. Bossert, who has publicly warned that as many as 500,000 Americans may ultimately die of the coronavirus, denied on Thursday that he had tried to see Mr. Trump and been unable to, but would not elaborate on his contacts with the White House. Some officials there also denied that he had made extensive efforts to speak with Mr. Trump or Mr. Pence.

Among the advisers who share the president’s more jaundiced view is his son-in-law, Jared Kushner, who considers the problem more about public psychology than a health reality, according to people who have spoken with him. Mr. Kushner has gotten more involved in the response in recent days, according to three White House advisers. A person close to Mr. Kushner said his views were being misinterpreted, and that he was focused on trying to find answers to the most immediate measures to mitigate the virus’s spread.

Marc Short, Mr. Pence’s chief of staff, approached Mr. Kushner on Monday about integrating the White House teams working on the issue, as the vice president’s communications shop is overrun with media requests and the White House is changing the chief of staff. After that, Mr. Kushner seized more of a role, spending Wednesday with Mr. Trump, the officials said.

One administration official said on Thursday that Mr. Kushner, his wife, Ivanka Trump, and Hope Hicks, a presidential adviser who has just returned to the White House, favored Mr. Trump giving Wednesday night’s prime-time address to calm the waters amid rampaging uncertainty and fear.

Ms. Trump, the president’s elder daughter, in particular favored the address, according to three administration officials. But the subject quickly became contentious internally, according to several administration officials. Drafts were written and rewritten, beginning around 5 p.m., with Mr. Kushner seen as in charge as the president’s chief speechwriter, Stephen Miller, wrote, and the communications office of the West Wing left out of the discussions.

By early evening, only two hours before the camera was to go on, it was still not entirely clear what Mr. Trump was going to say. In a meeting in the Cabinet Room, a number of top officials told the president the speech was a good idea, with a notable exception being the Treasury secretary, Steven Mnuchin, who said that Mr. Trump ought to wait at least a day or two so as to provide officials with more information. The president told aides gathered in the room, who disagreed on exactly how far he should go in terms of a travel ban from Europe, to come up with something and bring it to him, according to a person with direct knowledge of the events.

The health experts were either supportive of or neutral about a proposed ban on some European travelers, even as Mr. Mnuchin disagreed, and so the plan moved forward, with other items — like more specific recommendations for schools and crowds — left unmentioned.

When the camera turned on, the president appeared uncomfortable, reading words from the teleprompter in a stiff manner that made no emotional connection to a television audience of millions scared about a virus they cannot see and uncertain about a society rapidly transforming around them.

Even with the text on the screen, the president mischaracterized his own policies in a way that required his administration to correct him afterward. Administration officials said there were two errors in the teleprompter text, and one that Mr. Trump garbled as he read it, adding the word “only” in a sentence that was intended to say the ban did not apply to trade and cargo, a line that spooked markets.

He referred to the pandemic as a “foreign virus” that “will not have a chance against us” as if it were a hostile nation to be defeated on the battlefield. But while he talked about measures to prop up the economy, he did not discuss the troubles with the availability of testing kits or express understanding of the changes in everyday life affecting so many Americans.

Some close aides did not think the errors in the speech were particularly significant. By Thursday morning, it was clear that the speech had not assuaged the financial markets, which plummeted another 10 percent, the worst single day since Black Monday in 1987. Together with the losses of recent weeks, the markets have now erased about 85 percent of the gains of the entire Trump presidency, gains that were the foundation of his argument for re-election.

“Real leadership in this crisis is going to have to come from governors, from public health officials and from institutional leaders,” Rod Dreher wrote on The American Conservative’s website. “We saw tonight that even when Trump is trying to be on his best behavior, he just doesn’t have much of a clue about the nature of the crisis, or how it can best be fought.”

Others were more willing to give him some benefit of the doubt. Rich Lowry, the editor of National Review, which had just harshly criticized the president’s “failures of leadership” in handling the outbreak, saw some progress in the speech even as he expressed concern that it would not last.

“The speech represents a marked, welcome improvement in the president’s rhetoric,” he wrote, “but that won’t matter if he goes out and undercuts it tomorrow, and the ultimate verdict on his response will be rendered based on the results.”

The Wall Street Journal’s conservative editorial page likewise called the speech “a step toward more realism” but added that Mr. Trump was not forthcoming enough about the scope of the problem.

Republicans close to the White House privately laid blame at the feet of Mr. Kushner. A person close to Mr. Kushner described that as unfair, saying that he was merely helping out and that it becomes easier to blame him when things are difficult. And in any case, a partial travel ban on Europe was a bold move that may have been bound to rattle the markets rather than calm them no matter what.

The White House insisted that the president’s actions have had the support of health officials, and that local communities should make decisions based on their own conditions. Aides said the speech demonstrated to Americans that Mr. Trump understands the situation and is determined to react strongly to guard their well-being.

“The reaction has been very favorable across the country,” Mr. Pence said Thursday on Fox News.

Speaking on NBC’s “Today” show, Mr. Pence agreed it was wrong to dismiss the outbreak as hype. “Obviously there’s been some irresponsible rhetoric, but the American people should know that President Trump has no higher priority than the health and safety and well-being of the people of this country,” he said, without identifying who was responsible for the irresponsible rhetoric.

As for Mr. Trump’s call on Washington in his speech to “stop the partisanship,” that lasted just nine hours, at least some of which he was presumably asleep. By dawn on Thursday, he had already tweeted or retweeted attacks on Senator Chuck Schumer of New York, the Democratic leader, and Speaker Nancy Pelosi.

Peter Baker reported from Washington, and Maggie Haberman from New York.