A video shows the moment Joe Biden called an Iowa voter a “liar” and challenged him to a push-up contest after the man questioned Biden over his son’s work for a Ukrainian energy firm.

Biden lashed out at the man at a town-hall event in Iowa Thursday.

“We all know Trump has been messing around in Ukraine,” the man said.

“You on the other hand sent your son over there to get a job and work for a gas company and had no experience in natural gas,” he said. “You’re selling access to the president just like he is.”

Biden responded: "You're a damn liar, man. That's not true. And no one has ever said that."

As the two talked a staffer tried to take the man's microphone, but Biden waved her away so the man could continue to speak.

You can see the video below:

"Let him go. Let him go," Biden said.

"The reason I'm running is because I've been around a long time, and I know more than most people know, and I can get things done. And that's why I'm running."

He then addressed the man's criticisms of his age and fitness, challenging the man to a physical showdown.

"Let's do push-ups together here, man," he said. "Let's run. Let's do whatever you want to do. Let's take an IQ test."

"No one has said my son has done anything wrong," Biden added, saying he "did not on any occasion" do anything wrong and that "no one has ever said it."

"I didn't say you were doing anything wrong," the Iowa man said.

"You said I set up my son to work on an oil company," Biden said. "Isn't that what you said? Get your words straight, Jack!"

Hunter Biden

Foto: Hunter Biden.sourcePaul Morigi/Getty Images for World Food Program USA

Biden then appeared to call the man "fat," but Biden's campaign disputed this and insisted he had said "fact."

Attempts by Trump and key aides to pressure Ukraine to announce an investigation into Biden have sparked the first impeachment investigation in two decades.

The former vice president has been accused of seeking the dismissal of a Ukrainian prosecutor to help his son Hunter, who was serving on the board of the energy firm Burisma. No compelling evidence has emerged to support the claim, which is at the heart of GOP attacks on Biden's candidacy.

Democrats say Trump abused his office in seeking to enlist Ukraine to tar Biden and perhaps help Trump win reelection at the same time Trump was withholding nearly $400 million in military aid to Ukraine.