The White House projected the U.S. could face 100,000 to 240,000 deaths from the coronavirus pandemic, as President Trump warned Americans to brace for an unprecedented crisis in the days ahead.

“This could be a hell of a bad two weeks,” Mr. Trump said during a briefing at the White House on Tuesday afternoon, then quickly expanded upon his own dire assessment: “This is going to be three weeks like we’ve never seen before.”

The...