(CNN) -- President Donald Trump warned of a "painful" and "tough" two-week stretch ahead as he extended nationwide distancing measures that -- even if followed closely -- could still mean more than 100,000 and up to 240,000 Americans die from coronavirus.
It was a stark message from a President who spent weeks downplaying the severity of the virus and questioned its potential impact in the United States.
Trump did not minimize what has become the gravest public health crisis in decades during his remarks on Tuesday. Instead, he advised Americans that darker days may be still to come.
"I want every American to be prepared for the hard days that lie ahead. We're going to go through a very tough two weeks," Trump said.
He was speaking during a White House news conference meant to formally reissue nationwide coronavirus guidelines after Trump -- faced with dire models showing hundreds of thousands of potential American deaths, polls indicating support for social distancing and calamitous scenes at New York hospitals -- determined another 30 days were necessary to avert disaster.
After he spoke, the top health officials on Trump's task force presented a series of slides showing their models for how the social distancing measures might help prevent potentially millions of deaths.
But in a dire prediction, Dr. Deborah Birx said that even if the federal guidelines are followed precisely up to 240,000 deaths could still occur.
Officials were quick to say they didn't accept that figure as predetermined. But the model laid bare the potential devastation the outbreak could inflict.
"We gotta brace ourselves," Dr. Anthony Fauci, another top medical expert on Trump's team, told reporters. "We are continuing to see things go up. We cannot be discouraged by that because the mitigation is actually working and will work."
Not all of Trump's advisers supported the decision to extend the distancing guidelines, and some have privately questioned the models his health advisers used to convince him the distancing efforts were necessary, multiple people familiar with the matter said. Trump faced intense pressure from business leaders and some conservative economists to reopen some parts of the country before ultimately deciding against it.
Amid the internal debate over whether to ease the social distancing efforts, some aides recommended the President only extend them another 15 days, but health advisers argued a month was necessary, people familiar with the discussions said. Trump told aides it would be better to ease the guidelines earlier than expected rather than have to extend them again.
The guidelines are expected to last until April 30.
Trump has explained his decision as a necessary one to protect potentially millions of lives. To that end, Trump and the coronavirus task force delved into more detail on their models using graphs and information during the daily late-afternoon press briefing at the White House on Tuesday.
Those predictions don't have universal support inside the White House. There remains a concern among some skeptics on Trump's team that Birx and Dr. Anthony Fauci have put stock in models that could be wrong.
Epidemiological models rely on assumptions and can't, by their nature, always be 100% accurate. Much about the virus's spread remains unknown, particularly with persistent problems on getting Americans tested.
Trump himself seemed preoccupied with another figure -- 2.2 million -- during Sunday's briefing. An earlier study from the United Kingdom projected that number of potential American deaths if mitigation efforts weren't taken seriously.
Tuesday marks the expiration of the initial 15-day period for the federal social distancing guidelines that Trump announced earlier in March. He announced Sunday the guidelines would be extended another 30 days but indicated there might be some alterations.
"We will be finalizing these plans and providing a summary of our findings, supporting data and strategy to the American people," Trump said Sunday. "So, we'll be having lots of meetings in between, but we'll be having a very important statement made on Tuesday, probably Tuesday evening, on all of the findings, all of the data, and the reasons we're doing things the way we're doing them."
The team also plans to spell out steps its taken to increase testing and surveillance of coronavirus cases in individual states, a key component to containing the spread. Health experts have warned that without adequate testing, it's impossible to know how many people have been infected and which areas are better off.
Contact tracing -- the practice of determining who an infected person may have interacted wit -- also requires robust testing efforts, and is another step experts have said is necessary to containing the virus.
Speaking on CNN, Fauci said Tuesday that social distancing measures were bearing some initial results.
"We're starting to see glimmers that that is actually having some dampening effect," he said.
"I don't want to put too much stock on it because you don't want to get overconfident, you just want to keep pushing in what you're doing," Fauci added. "You're starting to see that the daily increases are not in that steep incline, they're starting to be able to possibly flatten out."
Fauci and Birx presented Trump the models showing between 100,000 and 200,000 deaths during an Oval Office meeting on Sunday that seemed to resonate and helped him finalize his decision.
"He looked at them, he understood them, and he shook his head and said, 'I guess we got to do it,' " Fauci said.
CNN also reported on Monday morning that Trump was struck by grave images from Elmhurst Hospital in Queens, near where he grew up, showing hospital workers inundated with coronavirus cases. The scene helped solidify his decision that further distancing measures were necessary to prevent the disease from spreading.
Polling presented to Trump also helped him determine that asking Americans to keep refraining from going to crowded workplaces or schools would not necessarily be unpopular.
As Trump codifies the extension of the guidelines, he and his advisers are weighing another recommendation with potential political fallout: that Americans being wearing masks or other face coverings, a reversal from earlier federal guidance that indicated such a step wasn't necessary.
Trump appeared open to the idea during Monday's press briefing, but said he didn't anticipate making a long-term mandate on mask-wearing.
"I could see something like that happening for a period of time. But I would hope it would be a very limited period of time," he said.
Fauci told CNN on Tuesday it would be up for "very active discussion" by the task force.