New Jersey governor and presidential contender Chris Christie shot back at critics of his hawkish national security policy Thursday, defending National Security Agency bulk data collection and attacking 2016 rival Rand Paul for his stance against surveillance practices adopted in the wake of 9/11.

“The problem with Senator Paul is that he’s never done this, and he doesn’t understand it,” Christie told Fox News’ Greta Van Susteren during “On the Record” Thursday. “When he makes the ridiculous statement that, ‘I want to take more from terrorists and less from innocent people,’ — how do you know Greta? And then he yells, ‘Go get a search warrant.’ Well, that’s not the way it works.”

Paul made the statement in response to a question about national security and surveillance in preventing terrorism during Fox’s first 2016 GOP primary debate last week, which set off a scrap with Christie.

“I want to collect more records from terrorists, but less records from innocent Americans,” Paul said. “The Fourth Amendment was what we fought the Revolution over. John Adams said it was the spark that led to our independence, and I’m proud of standing for the Bill of Rights, and I will continue to stand for the Bill of Rights.”

“That’s a completely ridiculous answer,” Christie cut in to Fox’s Megyn Kelly. “‘I want to collect more records from terrorists but less records from other people.’ How are you supposed to know, Megyn?”

“Use the Fourth Amendment. Get a warrant!” Paul countered. “Get a judge to sign the warrant!”

“Listen senator,” Christie continued. “You know, when you’re sitting in a subcommittee just blowing hot air about this, you can say things like that. When you’re responsible for protecting the lives of the American people, then what you need to do is to make sure you use the system the way it’s supposed to work.”

Paul went on to say he doesn’t trust the president with Americans’ phone records, and accused Christie of “fundamentally” misunderstanding the Bill of Rights. Christie chastised Paul for playing politics with a national security issue during the Senate vote in May to adopt the USA Freedom Act NSA reform bill, and “cutting speeches on the floor of the Senate” and  “putting them on the Internet within half an hour to raise money for your campaign and while still putting your country at risk.”

RELATED: Senate Passes USA Freedom Act

When asked why he couldn’t get a search warrant, Christie told Van Susteren “if you don’t have probable cause, you can’t get a search warrant.”

“Let’s remember something — we had in, pre-9/11, we had folks over here who had no apparent terrorist ties, but were getting phone calls from people who did have terrorist ties from out of the country. If we had had the NSA program then, we very well could have matched those phone numbers up, that would have been — given us probable cause to go after the folks who were here in the country before 9/11.”

“I don’t know if that would have prevented 9/11, but it would have given us a much better chance than the one we had,” Christie continued. “Senator Paul doesn’t understand this because when you’re in Congress — and this is why the American people have no respect for Congress — they don’t have to do anything. They’re not responsible for anything. I was the U.S. Attorney post-9/11, and I was responsible for protecting the lives of our citizens. When you have that responsibility, I’ll tell you this, as president of the United States, there’s not one step within the law that I wouldn’t take to prevent the killing of one American. And that’s the difference between me and Senator Paul.”

Fox’s own senior judicial analyst and former New Jersey Superior Court Judge Andrew Napolitano went after Christie in a Thursday op-ed over the governor’s debate comments, and said Christie’s stance flies in the face of the Fourth Amendment, which Paul interprets correctly.

RELATED: Napolitano: There’s Only One Pro-Fourth Amendment GOP Candidate, and It’s Not Chris Christie

“Christie advocated an approach more radical than the president’s when he argued with Paul during the debate last week,” Napolitano wrote Thursday. “He actually said that in order to acquire probable cause, the feds need to listen to everyone’s phone calls and read everyone’s emails first.”

“He effectively argued that the feds need to break into a house first to see what evidence they can find there so as to present that evidence to a judge and get a search warrant to enter the house.”

Napolitano went on to dub Paul the only candidate in the GOP field to take a stand on the strict constitutional application of the law.

“He is not against all spying,” Napolitano wrote. “Just against spying on all of us.”

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