President Trump on Sunday blasted Mark Cuban, saying the billionaire is not smart enough to run for the White House.

"I know Mark Cuban well," the president tweeted.

"He backed me big-time but I wasn't interested in taking all of his calls.He's not smart enough to run for president!"

I know Mark Cuban well. He backed me big-time but I wasn't interested in taking all of his calls.He's not smart enough to run for president! — Donald J. Trump (@realDonaldTrump) February 12, 2017

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Cuban was critical of Trump during his presidential campaign and supported 2016 Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Virginia Democrat blasts Trump's 'appalling' remark about COVID-19 deaths in 'blue states' The Hill's Campaign Report: Biden asks if public can trust vaccine from Trump ahead of Election Day | Oklahoma health officials raised red flags before Trump rally MORE. He said in an interview last May he would consider a future run for president. But in an interview in September, Cuban said there was "no possible way" he would run for the office.

The New York Post published an article Sunday, citing sources close to the White House who called Cuban the White House's "biggest fear" because he would garner votes from both Republicans and independents.

According to the publication, the White House is already looking into Democrats who could challenge Trump in 2020.

The Dallas Mavericks owner told The Star-Telegram last week that CEOs are in a "tough situation" with the president.

“You want to make nice with the president because you’re a public company and you have shareholders," he said, "and it’s hard to balance doing the right financial thing versus doing what they think is the right thing, whatever your political beliefs are. It’s not an easy position to be in.’’

He said he would recommend that CEOs "do what you think is right."

"Be an American citizen first," he said.

Earlier this month, Cuban criticized the president's travel ban, calling it a "horrible" misstep.

“It was half-baked, it wasn’t thought out, it was rushed, and it was ridiculous. When something like this happens, it calls into question the management skills of the guy in charge," Cuban said during an interview on CNN.