As the issue of sexual harassment has swept through the news media, politics and entertainment industries, Mr. Trump has persisted in denying allegations that he, too, made unwanted advances on multiple women in past years. In recent days, he has continued to seed doubt about his appearance on the “Access Hollywood” tape, stunning his advisers…

Mr. Trump’s falsehoods about the “Access Hollywood” tape are part of his lifelong habit of attempting to create and sell his own version of reality. Advisers say he continues to privately harbor a handful of conspiracy theories that have no grounding in fact.

In recent months, they say, Mr. Trump has used closed-door conversations to question the authenticity of President Barack Obama’s birth certificate. He has also repeatedly claimed that he lost the popular vote last year because of widespread voter fraud, according to advisers and lawmakers.