"The president of the United States calls the shots", Trump said during a combative press conference in which he feuded with reporters.
Two White House officials said there was no broader planning for Trump's comments that he had "total" authority.
Determined to quickly reopen the United States economy when the coronavirus threat eases, Trump warned governors and local leaders he would step in, if they insist on maintaining their own rules to prevent the spread of the virus beyond what he believes is necessary.
Trump, facing re-election on November 3 and under pressure to get the economy going again after millions have been made jobless by the shutdown, said some states should be able to reopen soon, based on a low rate of infections.
It gives guidance to state and local governments on how they can ease mitigation efforts, moving from drastic restrictions such as stay-at-home orders in a phased way to support a safe reopening. "To some extent, top public health officials and governors are working around the president for precisely the reason that we just saw unfold in front of our very eyes over the last hour", he said, "and that is: The president doesn't sound like he's in control on multiple levels".
"I have to go by the Fauci mantra: 'I'm always honest, '" Fauci said.
After receiving bipartisan blowback from his remarks, Trump on Tuesday attempted to backpedal his stance, saying that he would be coordinating with state governors to "authorize" the restart of their respective states' economies.
It is the latest development in a row that has been rumbling on for weeks over Mr Trump's eagerness to reopen the U.S. economy and loosen social distancing rules, despite warnings from health experts and political opponents.
However, many experts doubt the president has such powers.
At the same time, Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, echoed the expectation the data would be out within days or the coming week.
Dr Robert Redfield, the director of the Centers for Disease Control and Prevention, said Monday that he expected a reopening to play out "community by community, county by county" but that the U.S. would first need to "substantially augment our public health capacity to do early-case identification, isolation and contact tracing".
At Monday's briefing, Fauci downplayed any conflict with the president and insisted that he had been responding to a "hypothetical question".
Trump's main leverage then is to influence the disbursement of federal funds and other resources to the states, favouring those who back him and denying those he doesn't like.
"I am nearly positive James Madison fell off a cloud somewhere today when Trump said that, " said Dan Eberhart, a Republican donor. "I'm not firing. I think he's a wonderful guy". He said the USA would review the organizaiton's warning about the virus threat and China.
"That video has a gap for the entire month of February", Reid said in the briefing room.
Trump, who is head of the G7 this year, had planned to hold this year's summit at the presidential retreat of Camp David, Maryland, in June, but moved it to a virtual setting due to the virus.