He said he planned to travel to the Mexican border this week to “try to formulate policies that will seal the border permanently,” called for the federal government to consider the war in Ukraine from the perspective of Russians and said pharmaceutical drugs were responsible for the rise of mass shootings in America.

“Prior to the introduction of Prozac, we had almost none of these events in our country and we’ve never seen them in human history, where people walk into a schoolroom of children or strangers and start shooting people,” said Mr. Kennedy, who noted that both his father and uncle were killed by guns.

Mr. Kennedy said he now had “about 50 people” working for his campaign. Unlike Marianne Williamson, the other announced Democratic challenger to Mr. Biden, he does not appear to be aiming to appeal to Democrats who are ideologically opposed to the moderate president or are otherwise uneasy with renominating him. Instead, he has used his campaign platform — and his famous name — to promote misinformation and ideas that have little traction in his party.

Asked during the discussion by David Sacks, a top DeSantis donor who is also close to Mr. Musk, “what happened to the Democratic Party,” Mr. Kennedy spent nine uninterrupted minutes attacking Mr. Biden as a warmonger and claimed that their party was under the control of the pharmaceutical industry.

“I think the Democratic Party became the party of war,” Mr. Kennedy said. “I attribute that directly to President Biden.” He added, “He has always been in favor of very bellicose, pugnacious and aggressive foreign policy, and he believes that violence is a legitimate political tool for achieving America’s objectives abroad.”