COLORADO SPRINGS: US President Joe Biden took a face-first tumble on Thursday (Jun 1) after tripping over an obstacle on stage at the Air Force Academy in Colorado, but he appeared unhurt.

Biden, 80, who had delivered the commencement address to graduates of the military academy, had just shaken hands with a cadet and begun walking back to his seat when he fell.

Air Force personnel helped him back up and he did not appear to require further help.

As he rose, Biden pointed to the object that had apparently caught his foot.

Two small black sandbags were on stage supporting the teleprompter used by Biden and other speakers.

White House Communications Director Ben LaBolt tweeted shortly afterward that "he's fine. There was a sandbag on stage while he was shaking hands".

Biden is the oldest person ever in the presidency and is seeking a second term in the 2024 election.

He has been dogged by questions about his age and his fitness to serve, and his missteps have become fodder for political rivals as he campaigns for a second term in 2024.

He has stumbled before going up the stairs and onto Air Force One and he once got caught up in his bike pedals while stopping to talk to reporters near his home in Rehoboth Beach, Delaware.

Biden’s personal doctor said after the president’s most recent physical exam in February that Biden “remains a healthy, vigorous 80-year-old male, who is fit to successfully execute the duties of the Presidency.”

Dr Kevin O’Connor also documented the president's stiffened gait, which O'Connor said was the result of spinal arthritis, a previously broken foot and neuropathy in the Biden's feet.

Biden is far from the first national political figure to stumble in public.

President Gerald Ford fell down while walking off Air Force One in 1975. GOP Sen. Bob Dole of Kansas, the GOP presidential nominee at the time, fell off the stage at a campaign rally in 1996.

President Barack Obama tripped walking up the stairs to a stage at a 2012 event. “I was so fired up, I missed a stair” he told the crowd.

President Donald Trump's gingerly walk down a ramp at the 2020 West Point commencement also sparked concerns about his health.

Trump, 76, was campaigning in Iowa when he heard about Biden's stumble and alluded to his own episode.

“He actually fell down? Well I hope he wasn’t hurt,” Trump said after an audience member told him about what had happened to Biden. “The whole thing is crazy. You got to be careful about that ... cause you don’t want that, even if you have to tiptoe down a ramp.”

The audience laughed as Trump recounted slowly inching his way down what he said had been a slippery ramp at the US Military Academy graduation.

“If he fell, it’s too bad,” the former president said.

“We got to just get this thing back on track. That’s a bad place to fall when you’re making; I think it was the Air Force Academy, right? That’s not inspiring.”