Audience members at the second and final Wisconsin U.S. Senate debate Thursday were not happy when what was supposed to be an amicable exchange turned nasty.

Republican Sen. Ron Johnson debated Democratic challenger Lt. Gov. Mandela Barnes Thursday night at Milwaukee's Marquette University.

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Over the course of the debate, Johnson and Barnes traded barbs back and forth relentlessly.

At the end of the debate, both candidates were asked, "What do you find admirable about your opponent?"

Mandela Barnes and Ron Johnson are introduced before Wisconsin Senate debate

Republican U.S. Senate candidate Ron Johnson, right, and Democratic U.S. Senate candidate Mandela Barnes, left, are introduced during a televised debate Thursday, Oct. 13, 2022, in Milwaukee. (AP Photo/Morry Gash)

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Answering first, Barnes answered, "I do think the senator has proven to be a family man. And I think that's admirable. That's absolutely to be respected."

The senator answered next, saying he felt "likewise" toward Barnes.

Ron Johnson

U.S. Sen. Ron Johnson, R-Wis., arrives for a televised debate with Democratic challenger Mandela Barnes, Friday, Oct. 7, 2022, in Milwaukee. (AP Photo/Morry Gash)

"I appreciate the fact that Lt. Gov. Barnes had loving parents, school teacher, father that worked third shift. So he had a good upbringing," Johnson said.

"I guess what puzzles me with that is with that upbringing, why has he turned against America?" he continued. "Why does he find America awful?"

The senator was likely referencing statements from Barnes critical of the United States' founding.

Democratic U.S. Senate candidate Mandela Barnes answers a question during second debate

Democratic U.S. Senate candidate Mandela Barnes speaks during a televised debate Thursday, Oct. 13, 2022, in Milwaukee. (AP Photo/Morry Gash)

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The audience reacted with boos and jeers. 

Watch highlights from the Wisconsin Senate debate:

A Marquette University poll released this week showed Johnson with a six-point lead over Barnes in the final weeks before Election Day.