Jimmy McCain, son of the late Republican senator John McCain, plans to support Democratic presidential candidate Kamala Harris in the election campaign.
McCain told US broadcaster CNN on Tuesday that he had distanced himself from the Republican party and officially registered as a Democrat.
He criticized Republican presidential candidate Donald Trump, particularly condemning Trump's recent appearance at Arlington National Cemetery. Trump had laid a wreath at the cemetery in honour of US soldiers killed in an Afghan suicide attack three years ago.
Following the visit, there were reports of a confrontation between Trump's team and a cemetery employee, who was allegedly pushed aside when trying to enforce cemetery rules, according to the US military.
Trump faced accusations of using the visit for political gain.
The soldiers who are buried in the national cemetery, McCain said, could not decide for themselves whether they wanted to be used as a backdrop for an election campaign.
His father, John McCain, had been a vocal critic of Trump.
Trump was not invited to John McCain's funeral, and in 2020, McCain's widow endorsed Democratic President Joe Biden at the Democratic National Convention. Despite this, no immediate family member had previously left the Republican Party until now.
