Fox News/YouTube/screenshot
A focus group reacts to Donald Trump, left, and Sen. Ted Cruz (R-Texas).
Veteran pollster Frank Luntz said on "The Kelly File" that his focus group had overwhelmingly named Cruz as the winner of the Fox Business Network debate.
Luntz started by playing a clip of a feisty exchange between Cruz and real-estate mogul Donald Trump over the Texas senator's eligibility to be president.
"This is truly the highlight of the debate," Luntz said.
Trump argues that Cruz's birth in Canada could disqualify him from the Oval Office because the Constitution requires presidents to be "natural-born" citizens. Cruz argued that his American mother means that he was a US citizen at birth and thus eligible for the presidency. Many legal scholars agree with Cruz.
"I would suggest we focus on who's best prepared to be commander in chief because that's the most important question facing the country," Cruz said in the clip.
After Trump said there great legal scholars who think that Cruz could be disqualified, Cruz touted his legal background as Texas' former solicitor general.
"I've spent my entire life defending the Constitution before the US Supreme court, and I'll tell you, I'm not going to be taking legal advice from Donald Trump," Cruz quipped as the audience roared in approval.
Almost everyone in Luntz's focus group apparently thought that Cruz had schooled Trump on the issue.
"He handled him. It was really evident that he was capable of taking the hit and handling it, and turning Donald around on himself," one focus-group participant said of Cruz.
"Not only that," a man added. "He was very eloquent, very level-headed about everything that he had to say tonight. I like Donald Trump. Donald Trump is very opinionated, which doesn't make it easy for him during the debate."