The incident took place on Thursday at a campaign event in Iowa on Thursday when the 83-year-old Merle Gorman, who previously served in the US Marine Corp, accused Biden of selling access to the Presidency by sending son Hunter to Ukraine to work for a gas company Burisma Holdings, the Daily Mail said in the report.
Footage of the confrontation has now gone viral, with Gorman seen stating: "Trump has been messing around in Ukraine, he's (got) no backbone... But you, on the other hand, sent your son over there, gave him a job working with a gas company, he had no experience with gas or nothing, in order to get access for the President."
Biden was clearly enraged by the accusation, seen pacing the floor furiously before walking up to Gorman as if to confront him physically.
"You're a damn liar, man," Biden told Gorman. "That's not true."
Biden denied that he or his son engaged in any corrupt activity in Ukraine and told the voter to "get your words straight".
During the heated exchange, Gorman also told Biden (77) that he was too old to be running for office.
In response, Biden said that "you're too old to vote for me".
Meanwhile, Biden's camp has aggressively denied the former Vice President fat shamed Gorman, after he challenging him to the push-up contest, the Daily Mail reported.
Video of the incident suggests Biden said to Gorman at one point: "Look, fat, here's the deal."
The confrontation came the same day when House Speaker Nancy Pelosi lashed out at a reporter who asked if she "hated" President Donald Trump.
( With inputs from IANS )