The US President was boarding the plane for a trip to Pittsburgh, Pennsylvania to announced a $2 trillion bill for American infrastructure. But as rain poured down, Mr Biden gingerly walked up the stairs to Air Force One.
Video shows Mr Biden, holding an umbrella and a duffle bag, miss a step as he walked up the stairs of Air Force one.
Last month, the President tripped three times while climbing the steps ahead of a flight to Atlanta.
He recovered, and gave a salute to onlookers after the triple tumble.
Twitter users mocked the President’s gentle ascent, with one account calling Mr Biden “sick”.
Another user said: “He really does need a stair lift this is getting dangerous!”
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Some Republicans attack Mr Biden regularly for being “unfit” for office as the President is 79-years-old.
Sen. Mike Lee (Republican-Utah), texted an acquaintance in March comparing the President to someone he know’s who suffers from Alzheimer’s.
According to POLITICO, who saw the texts, he told his acquittance: “I of course have no medical training and can’t diagnose a condition — especially over someone I don’t personally interact daily — but from a distance I can see that he’s not doing well.
“Sad. And disturbing.”
Rep. Lauren Boebert (Republican-Colorado), a pro-Trump politician, also tweeted after his first fall: “President with cognitive decline is a national security risk.
“It’s time to stop dancing around that.”
After the March Air Force One gaffe, White House communications director Kate Bedingfield shared the President was not injured.
She said: “I know folks have seen that President Biden slipped on his way up the stairs to AF1, but I’m happy to report that he is just fine and did not even require any attention from the medical team who travels with him.”
Press secretary Karine Jean-Pierre also told White House pool reporters the President was “doing fine”.
She added: “It was very windy. I almost fell coming up the steps myself. He is doing 100 percent.
“He’s doing fine. He’s preparing for the trip just fine.”
The video of Mr Biden’s latest mishap comes ahead of his announcement of a $2 trillion infrastructure plan.
Speaking in Pittsburgh, the President described his proposal as a “once-in-a-generation investment in America”.
The American Jobs Plan aims to rebuild 20,000 miles of roads and highways and repair the 10 most economically significant bridges in the country, among other projects with a view to curb climate issues and create jobs.
To pay for the package, he proposed a substantial increase on corporate taxes that would offset the spending over the course of 15 years, rolling back former President Donald Trump’s tax-cut law.
Among the changes, Mr Biden called for a rise in the corporate tax rate to 28 percent from 21 percent, as well as measures to force multinational corporations to pay more taxes in the US on profits earned abroad.