SALEM, N.H. -- Sen. Ted Cruz (R-Texas) on Friday got into a heated exchange with a voter who accused him of supporting Syrian President Bashar Assad.

"I came from New Jersey to ask this question because it's so important to me," said John Davenport, a Fordham University professor who directs the school's peace and justice studies, during a town hall at Lancaster Elementary featuring the GOP presidential candidate.

"Supporting Assad is a mistake. He's the reason that ISIS exists in the beginning. What are you doing?" asked Davenport, who based his allegation that Cruz supports Assad on the failure of Congress to remove the Syrian leader from power.

Cruz, responding sarcastically, asked Davenport if he was undecided. When Davenport tried to respond, the crowd booed. One woman stood and yelled, “Stop it, and take your lithium."

“Even if others don’t show respect, we will show respect of civil discourse,” Cruz said. “This is how the First Amendment operates. I’m happy to have a respectful conversation.

“Now, your question begins with a false premise,” Cruz said to Davenport. “You asked me if I’m supporting Assad. I’m not supporting Assad.”

Cruz' standing in New Hampshire has slumped this month, according to HuffPost Pollster's aggregation of all available polls, putting him in third place in the GOP race in the final days before the primary.

The hostile exchange went back and forth for more than 10 minutes. As Davenport tried to elaborate, Cruz raised his voice and said sharply: “Sir, I’m happy to answer your question, but we are not having a debate.”

Cruz said President Barack Obama and then-Secretary of State Hillary Clinton led the 2011 NATO effort to topple Libyan leader Muammar Gaddafi, claiming the intervention created a vacuum that allowed the rise of radical Islamic terrorists. He suggested the same thing would happen in Syria if the U.S. ousted Assad.

Davenport passionately explained that Assad had killed 200,000 innocent Syrians. Cruz cut him off.

“We will not have a debate, Sir. I will answer it, but I will not have a yelling match,” Cruz said forcefully, as Davenport again tried to get a word in. “Alright, this answer is over,” Cruz shouted as the crowd erupted in applause.

Samantha-Jo Roth A sign John Davenport held at a Ted Cruz campaign event Friday in New Hampshire.

Davenport, 49, admitted his passion got the best of him.

“People are mad at me because I sounded angry tonight,” Davenport said later. “I wasn’t yelling obscenities. I’ll say for the record, there’s nothing more obscene in this world than hearing a politician support genocide. I got too angry because I care so much.”

Davenport said Cruz' answer contradicted statements he had made in the past.

“He said he doesn’t support Assad, but he wouldn’t take any actions to remove him from power,” Davenport said. “That’s basically putting him in alliance with Putin.”

Davenport, who said he considers himself a moderate independent, said other presidential candidates have views on Syria he finds more appealing.

“Marco Rubio does seem to take the right line on Assad, at least pretty close to it for that matter,” Davenport said. “So does Hillary Clinton, but not Bernie Sanders.”

With foreign policy playing a major role in the 2016 election, Davenport said that Cruz, along with other candidates, are overlooking Assad’s role in ISIS recruitment of Sunni fighters.

“Senator Cruz talks about attacking the root their ideology by keeping in place the very thing that fuels them,” Davenport said. "I don’t get why American politicians don’t understand that.”

Davenport acknowledged his exchange with Cruz caused quite a scene, but said he’ll continue to question presidential candidates on the topic to inform voters.

“I do care very much about fundamental human rights and genocide,” Davenport explained. “I don’t want to see any American politician ever coming close to accepting that as a reality, let alone saying how Christian they are in the process.”

Also on HuffPost:

PHOTO GALLERY Sen. Ted Cruz