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.

In contrast, Mr. Musk had posted more than 20 times on X this year about former President Donald J. Trump, the presumptive Republican nominee. In those posts, Mr. Musk defended Mr. Trump, arguing that he is a victim of media and prosecutorial bias in the criminal cases that the former president faces.

Mr. Musk’s posts about this year’s presidential race stand out because he is signaling a willingness to tip the political scales as the owner of an influential social media platform, something that no other leader of a social media firm has done. And Mr. Musk exerts outsize influence over the political discourse on X, where he regularly posts to his 184 million followers.

Mark Zuckerberg, Meta’s founder, has shied away from endorsing candidates and rarely posts political content on Facebook or Instagram. Satya Nadella, Microsoft’s chief, and Sundar Pichai, Google’s chief, have also not posted political commentary on their companies’ social media platforms, LinkedIn and YouTube.

Bhaskar Chakravorti, the dean of global business at the Fletcher School at Tufts University, said Mr. Musk’s outspokenness on his political views could have consequences.