Billionaire tech executive Elon Musk cast the upcoming presidential election in dire terms during a Saturday appearance with Donald Trump, calling the Republican presidential nominee the only candidate “to preserve democracy in America.”

The chief executive of SpaceX, Tesla and social media platform X, joined Mr Trump in Butler, Pennsylvania, where the former president survived an assassination attempt in July.

He warned that “this will be the last election” if Mr Trump does not win and, clad in a black-on-black cap bearing the “Make America Great Again” slogan of Mr Trump’s campaign, appeared to acknowledge the foreboding nature of his remarks.

“As you can see I am not just Maga — I am Dark Maga,” the SpaceX founder said.

The appearance marked the first time Mr Musk joined one of Mr Trump’s trademark rallies and represented the growing alliance between the two men in the final stretch of a competitive presidential election.

Mr Musk created a super political action group supporting the Republican nominee that has been spending heavily on get-out-the-vote efforts in the final months of the campaign.

Mr Trump has said he would ask Mr Musk to lead a government efficiency commission if he regains the White House.

Mr Trump joined Mr Musk in August for a rare public conversation on X, an overwhelmingly friendly chat that spanned more than two hours.

In it, the former president largely focused on the July assassination attempt, illegal immigration and his plans to cut government regulations.

During the rally on Saturday, Mr Musk sought to portray Mr Trump as a champion of free speech, arguing that Democrats want “to take away your freedom of speech, they want to take away your right to bear arms, they want to take away your right to vote, effectively.”

Mr Musk went on to criticise a California effort to ban voter ID requirements.

Saturday’s rally took place at the same property where a gunman’s bullets grazed Mr Trump’s right ear and killed his supporter, Corey Comperatore.

The shooting left multiple others injured.

Several members of Mr Comperatore’s family, as well as other attendees and first responders from the July rally, returned to the site on Saturday.

Also appearing with the former president were his running mate Republican Ohio senator JD Vance, son Eric Trump, daughter-in-law and Republican National Convention co-chairwoman Lara Trump.