WLD Biden-1575623050084
Democratic 2020 U.S. presidential candidate and former U.S. Vice President Joe Biden faces off with a local resident challenging him about his son Hunter Biden's involvement with Ukraine in this screen grab made from video shot during a Biden campaign event at Chickasaw Event Center in New Hampton, Iowa, U.S., December 5, 2019. Image Credit: REUTERS

Washington: For a candidate who has struggled at times to get noticed on social media, Joe Biden finally got some online attention on Thursday - for better or worse.

The normally affable Biden lost his composure at a campaign event in New Hampton, Iowa, on Thursday, sparring with a man in the crowd who questioned him about his role in the Ukraine scandal that has been dogging Trump.

“You’re a damn liar, man,” Biden told the man, who suggested without evidence that Biden had helped his son Hunter land a lucrative position with the Ukrainian oil company Burisma.

“No one has said my son has done anything wrong,” Biden said.

“Get your words straight, jack.”

Trump’s request that Ukraine launch an investigation targeting Joe Biden is at the center of the impeachment probe of the president being conducted by the U.S. House of Representatives.

Trump has accused the Bidens of corruption, without offering evidence. They have denied wrongdoing, and the allegations have not been substantiated.

The heckler at the Iowa event also questioned Biden’s fitness for office.

Biden responded by challenging the man to a push-up contest or an IQ test - and appeared at one point to call him “fat.”

The video of the exchange quickly made the rounds on Twitter.

Trump’s re-election campaign posted it, suggesting that Biden had gone “berserk.”

The 77-year-old former vice president continues to lead among Democrats in national polls and has so far withstood challenges from U.S. Senator Elizabeth Warren and others in the battle for the party’s nomination to take on Trump in the November 2020 election.