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The White House coronavirus response coordinator said Monday that she is "very worried about every city in the United States" and projects 100,000 to 200,000 American deaths as a best case scenario.

In an interview on "TODAY," Dr. Deborah Birx painted a grim message about the expected fatalities, echoing that they could hit more than 2 million without any measures, as coronavirus cases continue to climb throughout the country.

"I think everyone understands now that you can go from five to 50 to 500 to 5,000 cases very quickly," Birx said.

"I think in some of the metro areas we were late in getting people to follow the 15-day guidelines," she added.

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Birx said the projections by Dr. Anthony Fauci that U.S. deaths could range from 1.6 million to 2.2 million is a worst case scenario if the country did "nothing" to contain the outbreak, but said even "if we do things almost perfectly," she still predicts up to 200,000 U.S. deaths.

Fauci, the director of the National Institute of Allergy and Infectious Diseases, reiterated Monday on CNN that "I don't want to see it, I'd like to avoid it, but I wouldn't be surprised if we saw 100,000 deaths."

Birx said the best case scenario would be for "100 percent of Americans doing precisely what is required, but we're not sure that all of America is responding in a uniform way to protect one another," referencing images circulating online of people still congregating in big groups and ignoring guidelines from the Centers for Disease Control and Prevention.

Birx was also on "Meet the Press" on Sunday warning that "no state, no metro area will be spared," a message she repeated Monday. Even if metro or rural areas don't see the virus in the community now, by the time it does appear, the outbreak will be significant, she added.

How long Americans will be expected to comply with measures, including socially distancing and sheltering in place, remains unclear in this growing pandemic after several states and larger cities began implementing measures over the past couple of weeks.

President Trump announced Sunday that the administration's guidelines on social distancing have been extended until April 30. Trump said last week that he wanted to see much of the country return to normal by Easter, April 12, despite warnings from top health experts that easing guidelines early could cause mass deaths. Now, Trump said he expects "great things to be happening" by June 1.

Birx said on Sunday that the choice to extend the guidelines had not been made lightly.

"We know it's a huge sacrifice for everyone," she added.