By Yashwant Raj Washington, April 6 : Robert F. Kennedy Jr, a scion of the Kennedy family, joined the 2024 race for the Democratic presidential nomination, challenging incumbent Joe Biden. Kennedy filed his papers on Wednesday. Biden has not announced his presidential run yet, but is widely expected to seek a second term and has already soft-rolled his campaign visiting key swing states to tout his administration's achievement. He has said he has every intention of running, but it won't be official until he makes it official. Kennedy, 69, is President John F. Kennedy's nephew and Robert F. Kennedy's son. He has been a successful writer of fiction, but has been known in recent years for his anti-vaccination activism. He joins self-help author Marianne Williamson in the Democratic run, with just as remote a chance of securing the nomination. Williamson ran in 2020 as well but barely made an impression and exited the race, which was eventually won by President Biden. Kennedy's anti-vaccination peaked during the Covid-19 epidemic, partly fueling a wave of skepticism about the vaccines that experts hold responsible for many fatalities. AP news agency said Kennedy's anti-vaccine charity -- Children's Health Defense -- flourished during the epidemic and doubled its revenues to $6.8 million. Incumbent US presidents of either party have faced challenges from fellow party men and women -- called "primaried" -- but have never been unseated in modern US history. Kennedy Jr's uncle Edward "Ted" Kennedy had sought to unseat President Jimmy Carter, but failed. Carter lost his bid for a second term to Republican Ronald Reagan. And that was the last time that a Kennedy ran for the White House -- John F. Kennedy was first, and he won, but assassinated in office, Robert F. Kennedy was killed during the campaign. Robert F. Kennedy's son Joseph Patrick Kennedy II carried the family torch in US politics with several terms in the US House of Representatives, from the family's home state Massachusetts. Patrick Kennedy, the youngest son of Ted Kennedy, took over from him and served as a member of the US House of Representatives from Rhodes Island for several terms until 2011. And for the first time since the ascent of this storied family, there was no Kennedy in public office, but only for a while. Joe Kennedy III, Joseph Kennedy's son, took on the family mantle then, and served in the House of Representatives until 2020, when he ran to unseat incumbent Democratic Senator from Massachusetts Ed Markey, but failed. Now Robert F Kennedy Jr. /IANS