The mood inside the White House was gloomy, according to aides and people in contact with the president. Mr. Trump, who had no public events on his schedule, waited to see whether his dark closing message about the dangers of illegal immigration could once again help him defy the polls — this time showing that Democrats are likely to win control of the House and many governorships.

For days, Mr. Trump’s advisers have warned him that the losses could be brutal, even as they have said that the Senate should be a bright spot. Advisers acknowledge that Mr. Trump has a problem with women voters as he begins his own re-election effort.

Mr. Trump knows that his rhetoric may have gone too far at times, people close to him said, a sentiment which was reflected in an interview Mr. Trump had with an ABC affiliate owned by the Trump-friendly Sinclair Broadcasting.