Robert Kennedy Jr., With Musk, Pushes Right-Wing Ideas and Misinformation

Robert F. Kennedy Jr., a scion of one of the country’s most famous Democratic families, on Monday dived into the full embrace of a host of conservative figures who eagerly promoted his long-shot primary challenge to President Biden.

For more than two hours, Mr. Kennedy participated in an online audio chat on Twitter with the platform’s increasingly rightward-leaning chief executive, Elon Musk. They engaged in a friendly back-and-forth with the likes of Tulsi Gabbard, the former Democratic congresswoman turned right-wing commentator; a top donor to Gov. Ron DeSantis of Florida; and a professional surfer who became a prominent voice casting doubt on coronavirus vaccines.

Mr. Kennedy, who announced his 2024 presidential campaign in April, is himself a leading vaccine skeptic, and has promoted other conspiracy theories. Yet he has consistently hovered around 20 percent in polling of the Democratic primary, which the party has otherwise ceded to Mr. Biden.

On Monday, he sounded like a candidate far more at ease in the mushrooming Republican presidential contest.

He said he planned to…