Americans could see a first-of-its-kind fight as they prepare to celebrate the country's 250th independence: a cage match between the sons of a sitting US president, and the son of a former president.

The improbable possibility arose on Thursday when Hunter Biden, son of former Democratic President Joe Biden, challenged Republican President Donald Trump's eldest sons, Donald Jr. and Eric, to a fight.

Biden said he got a call from conservative social media commentator Andrew Callaghan, who told him that he was organising the match.

"I told him I'd do it — 100% in if he can pull it off. And if he can't, I'm still coming," he said in a video shared on Callaghan's Channel 5 Instagram.

The Trump Organization and White House did not immediately respond to requests for comments.

It is unclear if or when this match would happen.

The White House plans to host a similar event — but with actual UFC fighters — on June 14 as part of a series of events celebrating the semiquincentennial of the United States.

Biden became president after defeating Trump in the 2020 election, which the Republican continues to claim was the result of widespread fraud.

The threatened match between their sons has echoes of a proposed 2023 cage match between tech titans Mark Zuckerberg and Elon Musk, though that event never took place.

Earlier eras of American politics saw bloody political faceoffs, notably the 1804 duel between Vice President Aaron Burr and former Treasury Secretary Alexander Hamilton, which resulted in the former treasury secretary's death and effectively ended Burr's political career.