The United States' youngest congressman has said he won't "back down" after a naked video of him in bed was leaked.

Madison Cawthorn, 26, said the video showed him "being crass with a friend, trying to be funny".

"We were acting foolish, and joking. That's it," he said. "I'm NOT backing down...blackmail won't win."

The Republican, who is up for re-election in North Carolina, was first elected aged 25 - the minimum age for US Congress.

When he entered the national political arena, he was seen as a rising star in the Republican Party.

He beat then-President Donald Trump's endorsed candidate in the Republican primary, and went on to roundly defeat his Democratic rival in the general election in 2020.

But Mr Cawthorn, who was partially paralysed in a car accident in 2014, quickly attracted controversy.

The former real estate investor and motivational speaker faced backlash from his own party after claiming in a March interview that fellow lawmakers had invited him to orgies, and he had seen them taking cocaine.

He was also accused of denying medical and family leave to a former congressional staff member before firing her - which he denied.

House Minority Leader Kevin McCarthy, the top congressional Republican, recently said Mr Cawthorn had to "turn himself around".

"I just told him he's lost my trust, and he's going to have to earn it back," Mr McCarthy said.

Mr Cawthorn also faced rebuke after a video surfaced of him calling Ukrainian President Volodymyr Zelensky a "thug" and the Ukrainian government "incredibly evil".

And last month, Mr Cawthorn was cited for bringing a loaded handgun through airport security at a North Carolina airport.

In this most recent episode, leaked video appears to show Mr Cawthorn naked in bed and making thrusting motions on top of an unidentified person.

The video was released by American Muckrackers, a political fundraising group that opposes Mr Cawthorn.

In a statement, the group said they obtained the video from an anonymous source who used to be a donor for Mr Cawthorn's campaign.

The leak comes just days before the 17 May primary election for his congressional seat in North Carolina, where he faces several Republican challengers. Early voting is already underway.