Trump picks a new fight, this time with Forbes

Trump: Forbes doesn't understand my assets

Move over, Jeb Bush, Carly Fiorina and Fox News — Donald Trump has somebody else to argue with.

It's Forbes magazine and its new estimate that his net worth is just $4.5 billion, less than half Trump's claim of more than $10 billion.

"I'm a private company," he said in an interview at Trump Grill, the restaurant on the lower level of Trump Tower in midtown Manhattan. "I like the people at Forbes," he said, but added: "They don't really know my assets very well."

Donald Trump speaks with CNBC's John Harwood at the Trump Grill in New York.
Adam Jeffery | CNBC

For example, he said, "they don't give you any value for brand, and my brand is very valuable." Just minutes after our interview, he noted, he was returning to his office to sign a new branding deal worth "hundreds of millions of dollars."

"I'm sure they said I'm very liquid," Trump said.

Actually, Forbes called Trump much less liquid than he claimed. His own estimate, the article reported, was $793 million in cash and cash equivalents. The Forbes estimate: $327 million.

If that's correct, the $100 million Trump has vowed to spend on his campaign would consume nearly one-third of his cash.

"They're wrong," Trump said when told those numbers. "I have a lot of cash. I have hundreds of millions of dollars of cash."

Moreover, Trump noted that the media coverage he's received so far has allowed him to lead the polls while avoiding heavy advertising spending and conserving cash. "I'm under budget and ahead of schedule, like my projects," he said.

Asked about Trump's complaint, Forbes Editor Randall Lane said: "Our story speaks for itself."

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Carly Fiorina speaks with CNBC's John Harwood at Arnie's Place in Concord, N.H., on Sept. 13, 2015.
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Ultimately, Trump suggested it doesn't matter that much whose estimate is right.

"I don't know. Whatever it is," Trump concluded. "Do you agree it's a lot?"

No argument there.