Donald Trump sidekick JD Vance's was caught uttering a chilling threat as the president spoke to Congress, a lip-reading expert has claimed.

Vance, who once compared Trump to Nixon and Hitler, has transformed himself into his chief supporter. He was seen smirking while chatting with House Speaker Mike Johnson ahead of Trump's controversial speech, and saying the new president's enemies were about to get a "full reckoning".

Jeremy Freeman, a lip-reading specialist, claims that Vance told the Speaker: "Yes it is, a full reckoning, and long overdue." He also reportedly said: "By the way, I think the speech is going to be great. But I don't know how you do this for 90 minutes."

Johnson moved the microphone away to keep their conversation private. He replied: "The hardest thing was doing it during Biden, when his speech was a stupid campaign speech."

It's unknown who Vance is speaking about and threatening with a "full reckoning", reports the Express. There are plenty of candidates, but his comments came days after the heated sit-down with Ukraine's President Volodymyr Zelensky in the Oval Office. And it's not only the leader of the war-stricken country that has recently faced Vance's ire. He drew criticism this week for referring to Britain as a "random country".

Vance, who ascended to the role of US Senator in 2022, has defended Trump against his critics, attributing the failed assassination attempt in Pennsylvania last July to them. "The central premise of the Biden campaign is that President Donald Trump is an authoritarian fascist who must be stopped at all costs," he posted on Twitter shortly after the shooting incident. "That rhetoric led directly to President Trump's attempted assassination."

Trump's speech, where he lambasted his predecessor Joe Biden as "the worst president in American history", was met with enthusiastic applause from his supporters. In contrast, Democrats present in the room remained expressionless, with some holding up placards signs expressing their belief that Trump was favouring his billionaire friends with tax breaks at the expense of working-class families.

Oregon Senator Jeff Merkle said: "We cannot have business as usual while Trump and his unelected billionaire co-president Elon Musk are gutting many parts of the government that help working families thrive. The President tonight had the chance to change course, but instead, he came before the American people and doubled down on reckless plans to dismantle key federal agencies, disregard our laws, and dishonor our Constitution."