Former President Donald Trump on Saturday railed against fellow billionaire Mark Cuban, who has vigorously campaigned for his Democratic opponent, Vice President Kamala Harris.

“Mark Cuban is a loser,” Trump wrote in a Saturday Truth Social post. “While he was in the White House, he stopped answering his calls and became a rogue. He is a weak and pathetic ‘bully’, he has no control over anything. Really low clubhead speed, a total non-athlete!”

Trump’s insults came several days after Cuban mocked the Republican presidential candidate’s tariff proposals at a Harris campaign rally.

“Let me just tell you, this man has so little understanding of tariffs, he thinks China is paying for them,” Cuban said of Trump at a Harris rally in Wisconsin on Thursday.

Trump has proposed a universal tariff of 20% on all imports and an even higher rate of 60% on Chinese imports. The plan has been criticized by economists who point out that U.S. importers and consumers would ultimately bear the cost burden of such a harsh approach.

The animosity between two billionaires is a clear turning point from 2015, when Cuban praised Trump as “the best thing to happen to politics in a long time” in a “Fox & Friends” interview.

Trump, in turn, thanked him for the kind words.

The Cuban ultimately supported former Secretary of State Hillary Clinton in the 2016 election. And in the years since, his once friendly relationship with Trump has only grown icier.

This election cycle, Cuban-American has become a regular Harris surrogate on the campaign trail as the vice president works to portray herself as a pro-growth capitalist.

The former “Shark Tank” host may have his sights set on his own government position and, for example, has repeatedly floated the idea of ​​replacing Securities and Exchange Commission Chairman Gary Gensler.

Meanwhile, Trump has hired Elon Musk to replace his own mega-billionaire on the campaign trail, fueling another rivalry with Cuban.

“You can literally be one of the world’s greatest entrepreneurs of the last century and be a damn troll at the same time,” Cuban said of Musk in a Friday interview on “Real Time With Bill Maher.”