Is the verbal sparring unsettling former Vice President Joe Biden or President Trump?

"The Five" discussed the possible 2020 presidential election opponents as they continue to take shots at one another Tuesday.

"I would rather run against, I think, Biden than anybody. I think he is weakest mentally," Trump told reporters. "Joe Biden is a dummy."

Biden, the frontrunner in the Democratic presidential race, called the president an “existential threat to America” Tuesday in Iowa adding, “This is a guy who does everything to separate and frighten people.”

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On "The Five," Juan Williams said he thinks Biden is clearly under the president's skin.

"I'm telling you what's clear is that Joe Biden had unsettled Donald Trump. What he says Joe Biden is dumb or slow, please," Williams said.

However, co-host Jesse Watters disagreed, arguing instead that it was Biden who was "unsettled."

"I think Trump has unsettled Joe Biden because he flip-flopped on China today. He's had actually China is our competitor and is a huge threat," the "Watters' World" host said.

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Co-host Greg Gutfeld argued that Biden will say anything to keep the "spotlight."

"He is in a bad situation where the more you look, the less you see. He has cruised along as a co-star, secondary character in a sitcom, not the star. Now you know why because he will say anything for the spotlight," Gutfeld said.

Biden and Trump have repeatedly taken shots at one another in recent weeks, offering a glimpse of what a potential 2020 race would look like.

Biden, though, is leading the Democratic primary field by double digits in recent national polls.

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Nevertheless, Trump said he hopes to run against Biden in the 2020 general election.

Trump, who will be 73 on Friday, has repeatedly said he would “easily” beat Biden in 2020 and has poked fun at the former vice president’s age while giving the 76-year-old new nicknames including “Sleepy Joe” and “1 percent Joe.”

Fox News' Brooke Singman contributed to this report.