WATCH: Chris Christie vs. Rand Paul on NSA Surveillance

New Jersey Governor Chris Christie, a former federal prosecutor, and Kentucky Senator Rand Paul, a Libertarian who has fought against widespread government surveillance of American citizens, sparred over how to best protect the United States from terrorists.

Christie, who has said Paul would be to blame if another terrorist attack happened because he supports shutting down NSA surveillance programs, said he thinks surveillance is essential to protecting the country. Paul said he thinks it is unconstitutional to monitor American citizens without a warrant.