The pressure didn't sit well with Biden, which prompted him to give a heated response to the voter.
"We all know Trump has been messing around in Ukraine... but, you on the other hand, sent your son over there".
John Kerry, the former secretary of state and 2004 Democratic presidential nominee, is endorsing Joe Biden for president, buoying the former vice president's argument that his worldwide experience should be a deciding factor for voters in 2020.
"I'm not a Republican", he said.
"You're a damn liar, man" Biden yelled.
"You see it on TV?"
"I probably shouldn't have challenged him to pushups", Biden told reporters ahead of a campaign event with former Secretary of State John Kerry, conceding that hard questions are par for the court for presidential candidates. "One woman said she wanted to support Sen". Let's do push-ups together man, let's run, let's do whatever you wanna do.
Toward the end of their spat, Biden addressed the man saying, "Look, fat..."
In fact, reports that show Hunter Biden received compensation for his work at a Ukrainian oil company that far exceeds what a regular board member makes.
"You don't hear that on MSNBC", Biden said, getting closer.
He started talking about Ukraine, and how Biden's son Hunter held a high-paying job with the natural gas firm Burisma Holdings during the Obama Administration. The former vice president was speaking to a group of people in Iowa on Thursday when a man stood up to ask him a few questions. Iowa voters are concerned about Biden fostering a corrupt work environment during his time as Vice President. After the town hall was over, Biden told reporters that he was defending his son and that he did not lose to his temper.
Meanwhile, Biden, who would be 78 upon becoming president if he wins, has repeatedly defended his fitness on the campaign trail, noting that with age "comes wisdom".