President Trump said at a press briefing on Tuesday that the next two weeks in the U.S. will be "very painful" and that he wants "every American to be prepared for the days that lie ahead," before giving way to Deborah Birx to explain the models informing the White House's new guidance on the coronavirus.

Why it matters: It's a somber new tone from the president that comes after his medical advisers showed him data projecting that the virus could kill 100,000–240,000 Americans — even with strict social distancing guidelines in place.

On Sunday, Trump dropped his aspiration of reopening America by Easter after seeing the data and bleak hospital images out of New York, which is the epicenter of the crisis in the U.S.

The White House published health guidance on Tuesday as part of its new "30 days to slow the spread" plan, which would expire on April 30.

White House model for coronavirus deaths.

The big picture: Birx, the White House coronavirus task force coordinator, said at the briefing that estimates showed between 1 million to 2 million in the U.S. could die from the virus "without mitigation."

But with social distancing and strong public health measures in place, the "mountain" could be depressed to a "hill" that projects 100,000–240,000 deaths, Birx said.

"As sobering a number as that is, we should be prepared for it," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "Is it going to be that much? I hope not, and I think the more we push on the mitigation, the less likelihood it will be that number."

Trump, who has repeatedly compared the coronavirus to the seasonal flu, said at the briefing: "A lot of people have said 'Ride it out. Don't do anything, just ride it out. And think of it as the flu.' But it's not the flu. It's vicious."

Questioned about his change in tone, Trump said that the pandemic is "really easy to be negative about" but that he tries to maintain optimism and act as a "cheerleader for the country."

"We are going through the worst thing that the country has probably ever seen," he added. "We lose more here potentially than you lose in world wars. So there's nothing positive, there's nothing great about it, but I want to give people in this country hope."

Subscribe to Mike Allen's Axios AM to follow our coronavirus coverage each morning from your inbox.