"I just can't believe he called someone else an idiot," Watters said to his co-hosts. "Joe Biden, who's been in Washington for 40 years. That's his reputation."
Biden insisted he’s still the front-runner for the nomination. Downplaying the lack of an endorsement by former President Barack Obama, he defended his son Hunter's business dealings actions in Ukraine, and called Trump an “idiot,” as he faced tough questions during an interview broadcast Sunday night on "60 Minutes."
"He's an idiot, in terms of sayin' that. Everybody knows this. Everybody knows it. Nobody doubts it,” Biden said, responding to Trump's comments that Russian interference in American elections is a "hoax."
Watters said Biden's reaction show's that he is being "sucked in" by President Trump -- and that's bad news for Biden.
"That's exactly where Trump wants him, because Trump's the king of the schoolyard," Watters said. "And Biden's whole appeal is that I'm going to restore decency to the White House. And then he's now name-calling with the president. It's not a good look."
The "Watters' World" host also blasted the politician for defending his son Hunter's Ukraine involvement.
"He lied about his son. He was appointed point for Ukraine. Then his son got the job and Burisma, not the other way around. And CBS let him get out of the way with that," Watters said. And then also, you're saying your defense on that is ignorance."
Watters added: "That's your defense. Not a good defense."
Fox News' Paul Steinhauser contributed to this report.