Mr. Meadows called into Fox News on Saturday night, knowing the president was most likely watching, and praised his “unbelievable courage” and “unbelievable improvement.” But he also confirmed that Mr. Trump’s condition on Friday was worse than originally described. “Yesterday morning we were real concerned with that,” Mr. Meadows said. “He had a fever and his blood oxygen level had dropped rapidly.”

The mixed messages only exacerbated the confusion and uncertainties surrounding the president’s situation. During their briefing on Saturday, the doctors refused to provide important details and gave timelines that conflicted with earlier White House accounts and left the impression that the president was sick and began treatment earlier than officially reported.

Two people close to the White House said in separate interviews with The New York Times that the president had trouble breathing on Friday and that his oxygen level dropped, prompting his doctors to give him supplemental