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

The CEO of SpaceX and Tesla who also purchased X, Musk joined Trump in Butler, Pennsylvania, on Saturday at the site where the former president survived an assassination attempt in July. Musk said “this will be the last election” if Trump doesn’t win. Wearing a cap with the “Make America Great Again” slogan of Trump’s campaign, Musk appeared to acknowledge the foreboding nature of his remarks.