US President Donald Trump on Sunday slammed former ally Elon Musk's launching of a new political party as "ridiculous," deepening the Republican's feud with the man who was once his biggest backer. Trump also branded the SpaceX and Tesla tycoon a "TRAIN WRECK" who had gone "off the rails" after Musk said he wanted to challenge the current US political system.

Elon Musk was almost inseparable from Trump as he headed the cost-cutting "Department of Government Efficiency," but they fell out hard over the president's "big beautiful" tax and spending mega-bill.

Donald Trump has lashed out at Elon Musk after the billionaire unveiled plans to launch a new US political party, calling him a “train wreck” in an escalation of the feud between the US president and his former ally.