Elon Musk, the billionaire chief executive of Tesla Inc (NASDAQ: TSLA) has officially launched a new political movement – the America Party – in a dramatic shift that’s rattling investors and reigniting tensions with President Donald Trump.

As a rule, third party candidates don’t win in the United States. Then again, a third-party bid has never had the backing of the world’s richest man.

Pointing his rockets at the “one big, beautiful bill” and its loyal lawmakers, Mr Musk threatened to blow up the two-party US system by doing what few have dared: launch one of his own. “If this insane spending bill passes, the America Party will be formed the next day,” he wrote in a string of firebrand posts on Monday.