“He’s the blame shifter in chief,” said Gwenda Blair, a Trump biographer. “Conspiracies, by definition, are things that others do to you. You’re being duped; you’re being fooled; the world is laughing at us. It goes to this idea that you can’t believe anything that you read or see. He has sold us a whole way of accepting a narrative that has so many layers of unaccountable, unsubstantiated content that you can’t possibly peel it all back.”…

Former aides to the president, speaking privately because they did not want to embarrass him, said paranoia predisposed him to believe in nefarious, hidden forces driving events. But they also said political opportunism informed his promotion of conspiracy theories. For instance, two former aides said Mr. Trump had resisted using the term “deep state” for months, partly because he believed it made him look too much like a crank.

But Mr. Trump saw that it played well in the conservative news media, and so in November, he began using it, the two aides said. The strategy appears to have yielded results. Several polls have shown a dip in public approval of the special counsel investigation over the past several months, as the president has repeatedly attacked it. And a Monmouth Poll released in March found that a bipartisan majority believes an unelected “deep state” is manipulating national policy.