Republican rivals Gov. Chris Christie of New Jersey and Sen. Rand Paul of Kentucky are escalating their feud over national security policy and liberty. In comments at a forum of Republican governors in Aspen, Col. Thursday, Mr. Christie said the libertarian strain championed by Mr. Paul currently coursing through the veins of political parties — as evidenced by broad, although ultimately unsuccessful, lobbying in the House of Representatives against NSA surveillance programs this week — is dangerous. “This strain of libertarianism that’s going through parties right now and making big headlines I think is a very dangerous thought,” Mr. Christie...