Robert F. Kennedy Jr has apologised to his family for any "pain caused" after an advert for his presidential bid was aired during the Super Bowl over the weekend.
The advert was an almost exact replica of one used by his late uncle, former president John F. Kennedy, in his successful 1960 election campaign.
The independent presidential candidate, who comes from one of the most influential political families in the US but has garnered a reputation for his anti-vaccine activism and far-right influences, denied any involvement in the ad.
"I'm so sorry if the Super Bowl advertisement caused anyone in my family pain," he wrote posted on the social media platform X, formerly known as Twitter.
"The ad was created and aired by the American Values Super PAC without any involvement or approval from my campaign."
Mr Kennedy launched his longshot bid for the US presidency in April 2023.
His cousin, Bobby Shriver, posted that his mother, JFK's sister Eunice Kennedy Shriver, would be "appalled by his deadly health care views."
Mr Shriver continued: "Respect for science, vaccines, & health care equity were in her DNA.”
Mr Kennedy responded separately to his cousin: “Bobby. I’m so sorry if that advertisement caused you pain. I send you and your family my sincerest apologies. God bless you.”
Aside from his family name, Mr Kennedy was best known as an environmental lawyer who fought for causes such as clean water.
But in the last two decades he has become a leading voice in the anti-vaccination movement.
As a result he has become distanced from many members of his family, who have described his work as misleading and dangerous.
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