WASHINGTON -- Former US Republican President George HW Bush plans to vote for Democratic presidential nominee Hillary Clinton, according to a niece of former US President John F Kennedy.

Along with a picture of her shaking hands with Bush posted Monday on her Facebook page, Kathleen Kennedy Townsend, former Maryland lieutenant governor and niece of late US President Kennedy, wrote in the caption that the 41st US president would buck his party's own nominee Donald Trump in this year's election.

"The President told me he's voting for Hillary!!" read the caption.

According to Politico, a spokesman for Bush replied to the US daily in a way that did not appear to refute Townsend's claim.

"The vote President Bush will cast as a private citizen in some 50 days will be just that: a private vote cast in some 50 days. He is not commenting on the presidential race in the interim," wrote the spokesman in an email.

According to an earlier statement by Bush who endorsed every Republican presidential nominee for the past five election cycles, for the first time since his own presidency, the 41st US president "is retired from politics," and had no plan to endorse Trump this year.