Donald Trump has a "minimal relationship with the truth," according to the GOP nominee's biographer David Cay Johnston.
"Donald makes up things he creates his own reality," Johnston said on CNBC's "Power Lunch" on Wednesday. "And in his mind, there's nothing wrong with that."
Johnston — a Pulitzer Prize-winning journalist — spoke out about Trump just after the release of his book, "The Making of Donald Trump." He said that Trump is "masterful" at two things: "Creating this image of himself as a modern Midas ... Secondly, at extracting money from enterprises, not building a business, not creating wealth."
Trump has so far declined to release his tax returns in a break with historical precedent, and Johnston — who reported on taxes for the New York Times — said Trump's returns would be very revealing, for example detailing how much his buildings are worth.
He also brushed off the potential that Trump's run was really meant to boost his business success.
"He's serious about this, Donald believes he should be president," Johnston said.
A Trump campaign spokeswoman did not immediately respond to a request for comment.