"Christie worries about the dangers of freedom. I worry about the danger of losing that freedom. Spying without warrants is unconstitutional," Paul (R-Ky.) tweeted.

Speaking at an event sponsored by the Aspen Institute, Christie denounced critics of the NSA programs and, though he avoided outright mention of Paul, made it clear that he had the senator — and potential 2016 GOP primary rival — in mind.

"This strain of libertarianism that's going through parties right now and making big headlines I think is a very dangerous thought," Christie said.

Asked if he was referring to Paul, Christie said: "You can name any number of people and he's one of them."

Christie defended the surveillance programs, and said President Obama did not shut them down after succeeding President George W. Bush because they work.

Those opposed to the programs should explain their beliefs to families of those killed in the Sept. 11, 2001 attacks, Christie said.

"These esoteric, intellectual debates —I want them to come to New Jersey and sit across from the widows and the orphans and have that conversation. And they won't, because that's a much tougher conversation to have," he said.

Christie said proponents of blocking the program would regret their stance if another terrorist attack happened.