Mr Biden, who turned 79 last week and is the nation’s oldest president, remains “healthy” and “vigorous” and fit for duty, Dr O’Connor said in his initial report after Mr Biden’s first routine physical in office. The president is showing some signs of aging, the doctor noted.

Mr Biden was placed under anaesthesia while undergoing the colonoscopy last week, briefly transferring presidential powers to Kamala Harris.

Presidents routinely invoke the 25th Amendment, which temporarily transfers power to the vice president, while under anaesthesia.

President George W Bush did so twice, transferring power to Dick Cheney when he underwent colonoscopies in 2002 and 2007.

Donald Trump’s former press secretary heavily implied the former president underwent an undeclared colonoscopy in 2019 but skipped anesthesia to avoid transferring power to his then-vice president Mike Pence.

A history of minor health scares

Mr Biden had his last full medical assessment in December 2019, when he was declared “healthy, vigorous” and “fit to successfully execute the duties of the Presidency”.

The president has had episodes of atrial fibrillation, a type of irregular heartbeat that is potentially serious but treatable.

Mr Biden’s most serious health scare was in 1988, when he required surgery to repair two brain aneurysms.

The health of Mr Biden, the oldest president to take office, has been a topic of intense scrutiny, particularly among Republicans who have claimed his regular verbal slip-ups are the consequence of his age and declining mental fitness.

A recent poll suggested Americans have increasing doubts about the president’s physical health and mental fitness.

In a Politico/Morning Consult poll last week, 50 per cent of voters said they did not believe Mr Biden was in good health, while 40 per cent said they did.