Donald Trump doesn't have clear contact with reality, though I'm not sure it qualifies as a bona fide delusion. He needs things to be a certain way even though they aren't, and that's one reason he lies. There can also be a conscious manipulative element to it. When he put forward, and politically thrived on, the falsehood of President Obama's birth in Kenya, outside the United States, he was manipulating that lie as well as undoubtedly believing it in part, at least in a segment of his personality.