Mark Cuban offers Donald Trump $10 million - 'if you need it' - to have 4-hour policy interview with him

Mark Cuban offered Donald Trump $10 million to let the billionaire businessman interview the Republican nominee for four hours about his policies.

Cuban, the owner of the NBA's Dallas Mavericks and star of ABC's "Shark Tank," presented the proposition in a scathing tweetstorm.

"$10mm to the charity of YOUR choice if you let ME interview you for 4 hrs on YOUR policies and their substance," Cuban wrote.

"@realDonaldTrump groundrules are that you cant mention the Clintons or discuss anything other than the details and facts of yr plans and no one else is in the room to help," he continued. "Just me, you and a broadcast crew. Deal?"

Cuban added "an option."

"If you need it, I'll write you the check and you can keep the money rather than give it to charity," Cuban posted. "In the immortal words of YOU. 'What do you have to lose?'"

His tweetstorm came in response to Trump's Friday morning interview with Fox Business host Maria Bartiromo, during which the Manhattan billionaire said Cuban was "really not smart enough" to understand Trump's economic plan.

Trump was responding to Cuban's claim that if the Republican nominee wins in the fall there was "no doubt in my mind the markets tank."

"Well, I know Mark, and you know the problem with Mark is, he's not smart enough to understand what we're doing," Trump said. "He's really not smart enough."

"I've known him for a long time - he tweets me all the time," Trump said. "He sends me so many different tweets and calls me, although I must say not over the last number of months. Because I said this guy ... he'll send out so many tweets. I'll have to send you all of the Mark Cuban tweets and conversations."

Trump doubled down on Cuban being "not smart enough" to understand his economic plans, asking Bartiromo and her fellow Fox Business hosts to "explain to Mark" that "we're in trouble."