Mark Cuban said Donald Trump has been getting "stupider" as the campaign progresses. | Getty Cuban: Give Trump credit for getting 'stupider'

Mark Cuban stepped up his criticism of Donald Trump’s campaign on Tuesday, this time attacking him personally.

“You know what? It’s rare that you see someone get stupider before your eyes, but he’s really working at it… You have to give him credit. It’s a difficult thing to do but he’s accomplished it,” the billionaire entrepreneur and Dallas Mavericks owner said in an interview with Extra.


Earlier on Tuesday, Cuban tweeted saying Trump “doesn’t have the cash” to fund his own campaign, following a Federal Election Commission report showing his campaign had $1.3 million compared to Hillary Clinton’s $42 million at the beginning of June.

Cuban also told "Extra" on the set of ABC's "Shark Tank" that the presumptive nominee had to “start learning and understanding the issues.”

“Donald has been at this a year but you don’t look at him and say, ‘Wow, he’s gotten so much smarter on this topic or that topic.' In fact, you look at him and say, ‘What the hell are you talking about?',” he added.

Trump, he remarked, would "get kicked out of 'Shark Tank' so fast, it would make your head spin.”