President Donald Trump on Tuesday warned of a "very painful" two weeks as the United States wrestles with a coronavirus surge that the White House warns could kill as many as 240,000 Americans.

"This is going to be a very painful, a very, very painful two weeks," Trump told a press conference at the White House.

Trump described the pandemic as "a plague."

"I want every American to be prepared for the hard days that lie ahead," he said.

Top health experts said that the decision to maintain strict social distancing was the only way to stop the easily transmitted virus, even if this has caused massive disruption to the economy with three quarters of Americans under some form of lockdown.

"There's no magic vaccine or therapy. It's just behaviors, each of our behaviors translating into something that changes the course of this viral pandemic over the next 30 days," Deborah Birx, coronavirus response coordinator at the White House, said.

Birx displayed a chart at the press conference charting a range of 100,000 to 240,000 deaths in the United States, when current efforts at mitigation are taken into account.

Infectious diseases specialist Anthony Fauci told the press conference that "mitigation is actually working" and that authorities are "doing everything we can to get it (the death toll) significantly below that."