Trump warns his former ally against backing any Democratic candidates to challenge the Republicans, as a messy feud between the two escalates.

US President Donald Trump threatened his former advisor Elon Musk with "serious consequences" Saturday if the tech billionaire seeks to punish Republicans who vote for a controversial spending bill. Some lawmakers who were against the bill had called on Musk -- one of the Republican Party's biggest financial backers in last year's presidential election -- to fund primary challenges against Republicans who voted for the legislation.

President Trump warned Saturday that his former ally Elon Musk will face “very serious consequences” if he starts bankrolling Democratic candidates for office after their nasty public split over a Republican spending bill working its way through Congress.