Democratic presidential candidate and former vice president Joe Biden got into an extraordinary exchange Thursday afternoon with an Iowa farmer who first called him too old to run and then challenged him on Hunter Biden’s activities in Ukraine, triggering Biden to call the man “a damn liar.”

During an event in New Hampton, Iowa, the man rose to say he had two issues with Biden’s candidacy.

“You’re damn near as old as I am,” the man started. “You’re too old for the job. I’m 83, and I know damn well I don’t have the mental faculties I did 30 years ago.”

Then he turned toward what he said was a more pressing concern.

“We all know Trump has been messing around in the Ukraine over there, holding their foreign aid . . . saying they’re going to investigate you,” he said. “He’s got no backbone, we know that.”

“But you, on the other hand, sent your son over there to get a job and work for a gas company that he had no experience with gas or nothing, to get access to the president,” he continued. “You’re selling access to the president just like he was.”

Biden stopped him. Although Hunter Biden was appointed to the board of a Ukrainian gas company while his father was vice president, there is no evidence that Joe Biden played any role in getting him the job or that Biden was “selling access to the president.”

“You’re a damn liar, man,” Biden said. “That’s not true. And no one has ever said that.”

“The hell it ain’t,” the man replied. “I see it on the TV.”

“You see it on the TV?” Biden said.

“All I do is watch TV,” the man continued.

“No, I know you do,” Biden responded, as he moved closer to the man, looked him in the eye and instructed one of his staffers not to take the microphone away from the man.

“And by the way, I’m not sedentary,” Biden, 77, continued. “Look, the reason I’m running is I’ve been around a long time, and I know more than most people know. And I can get things done, that’s why I’m running. And you want to check my shape, man, let’s do push-ups together here, man. Let’s run. Let’s do whatever you want to do. Let’s take an IQ test. Okay?”

“Number two,” Biden said. “No one has said my son has done anything wrong. And I did not on any occasion — and no one has ever said it.”

The Iowan interjected, saying, “I didn’t say you were doing anything wrong.”

“You said I set up my son to work on an oil company!” Biden said, growing more agitated and raising his voice. “Isn’t that what you said? Get your words straight, Jack!”

“That’s what I hear on MSNBC all day,” the man said.

“You don’t hear that on MSNBC,” Biden said.

“The hell I didn’t,” came the response.

“You did not hear that at all. What you heard — look, okay,” Biden said, trying to calm the exchange. “I’m not going to get in an argument with you, man.”

“I don’t want to either,” the man said.

“Well, yeah you do,” Biden responded.

“It looks like you don’t have any more backbone than Trump does,” the man said, as the crowd groaned.

Biden looked around.

“Any more questions?” Biden said, turning elsewhere in the audience.

As he sat down, the man said he wasn’t going to be voting for Biden.