President Trump took direct aim at Elon Musk on Sunday night and said the billionaire had gone “off the rails” after Musk announced plans to start a new political party.

“I am saddened to watch Elon Musk go completely ‘off the rails,’ essentially becoming a TRAIN WRECK over the past five weeks,” Trump wrote on Truth Social, The New York Times reported. “He even wants to start a Third Political Party, despite the fact that they have never succeeded in the United States.”

The president echoed those words when he spoke to reporters on his way back to Washington D.C. this weekend.

“He can have fun with it, but I think it’s ridiculous,” he said on Sunday. “I think it’s ridiculous to start a third party. We have had tremendous success with the Republican Party. The Democrats have lost their way, but it’s always been a two-party system, and I think starting a third party just adds to the confusion. It really seems to have been developed for two parties.”

Musk’s proposed party, which he’s calling the America Party, is the latest sign of a public falling out between the two men.

The two were once close, with Musk pouring hundreds of millions into Trump’s campaign and being rewarded with a major role overseeing government spending cuts as he was named the unofficial head of the Department of Government Efficiency (DOGE).

That relationship began to unravel last month when Trump’s sweeping domestic policy bill passed Congress.

Musk slammed the legislation, which was known as the One Big Beautiful Bill, as a “disgusting abomination.”

He also said he would back primary challengers against any Republican who voted for it. The bill still passed with overwhelming Republican support. Musk has not shared much about what the America Party stands for or who is involved in building it.