Tuesday marked the first presidential debate between President Donald Trump and former Vice President Joe Biden, and University of Central Florida history professor Dr. Jim Clark said he has never seen a debate like this. Clark mentioned Biden called Trump a liar three times in the first hour of the debate. [MORE COVERAGE: Chaotic first debate: Taunts overpower Trump, Biden visions]“I was surprised how quickly it turned into a brawl,” he said. He said Biden and Trump are trying to get their supporters to the polls. “I’ve never heard the word clown in a presidential debate,” he said.