Last month, Elon Musk posted on X that President Biden "obviously barely knows what's going on."

"He is just a tragic front for a far left political machine," Mr. Musk wrote. It was the 29th time this year that he had posted about the president on X, formerly known as Twitter, which Mr. Musk bought in 2022.

Mr. Musk has steadily ramped up his criticism of Mr. Biden as the campaign season heats up before the November presidential election. Mr. Musk has posted about Mr. Biden on X at least seven times a month since January, attacking the president for everything from his age to his policies on immigration and health. Before that, he posted about Mr. Biden twice in December and not at all in November, according to a New York Times analysis. In all, Mr. Musk had posted nearly 40 times about Mr. Biden this year, compared with about 30 times for all of last year.