Robert F. Kennedy Jr. speaks at a festival hosted by a libertarian group in Lancaster, New Hampshire, on June 22, 2023. (Ryan David Brown/The New York Times) Robert F. Kennedy Jr. is running for the 2024 Democratic presidential nominee. Anxious Democrats are taking note. The longtime environmental lawyer is the son and namesake of Robert F. Kennedy Sr., a former U.S. attorney general who was assassinated during his 1968 presidential run. John F. Kennedy, the slain 35th president, was his uncle. Advertisement RFK Jr. is political royalty. He is getting attention in Democratic circles, especially from older voters who remember...