Former Gov. John Hickenlooper, D-Colo. mocked Sen. Bernie Sanders, I-Vt. during a fiery clash over socialism at the Democratic debate Tuesday night by flailing his arms in the air.

Hickenlooper was confronted about his prior attacks on socialism, warning Democrats to not let "extremes" give President Trump four more years in the White House. CNN moderator Jake Tapper then asked him if he was saying that Sanders, a self-described Democratic Socialist, is "too extreme" to win the White House.

"I'm saying that policies of -- this notion that you're going to take private insurance away from 180 million Americans... or the Green New Deal -- make sure that every American is guaranteed a government job that they want- that is a disaster at the ballot box," Hickenlooper responded.

"You might as well FedEx the election to Donald Trump."

WATCH: BERNIE SANDERS, CNN ANCHOR JAKE TAPPER GET INTO IT DURING DEM DEBATE

Sanders shot back by citing "every credible poll" that he has seen showing him defeating Trump in a 2020 matchup, telling the audience he will defeat the president because he'll "expose" him for the "phony and fraud that he is."

Hickenlooper doubled down on his opposition to Sanders' policies and invoked his iconic body language in the process.

"Again, I think if we're going to force Americans to make these radical changes they're not gonna go along," Hickenlooper continued, seeing Sanders raise his arms as he was talking. "Look, throw your hands up!"

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"OK!" Sanders exclaimed while raising his arms even higher, causing a roar from the audience.

"Oh, I can do it!" Hickenlooper shot back as he raised his own arms. "You haven't implemented the plans. Us governors and the mayors are the ones who have to pick up all the pieces!"