You might not have guessed it from this weekend's "Commander In Chief" debate—where he was one of only two Republican presidential hopefuls not competing to be seen as the proudest torturer and most enthusiastic killer of terrorists and subversives—but Rep. Ron Paul (R-Texas) has fundamentally changed the terms of next year's presidential campaign.

If Paul is known for one issue as a politician, it is his detailed and longstanding critique of the Federal Reserve. Since 2008, "End the Fed" has emerged from the fringe and become a broadly popular position. When Paul expressed sympathy for the left-leaning Occupy Wall Street movement in the October 18 GOP presidential debate in Las Vegas, he was in the unusual (for him) position of expressing a centrist sentiment. Paul has also attracted some progressive support with his correct identification of the destructive force of crony capitalism and for having warned about the housing bubble back in 2003. He has been repeating similar economic critiques since long before a national audience was paying attention.

The other GOP candidates are now following in Paul's footsteps. In August, Michele Bachmann said the Fed made "terrible, grievous errors," while Perry famously declared that another round of stimulus spending by Fed Chairman Ben Bernanke would qualify as "treasonous." In the October 11 New Hampshire debate, which focused on the U.S. economy, former House Speaker Newt Gingrich said, "If [Occupy Wall Street protesters] want to really change things, the first person to fire is Bernanke, who is a disastrous chairman of the Federal Reserve."

Even Herman Cain, whose flirtation with front-runner status seems to have ended, has had a hard time maintaining his outsider appeal in the face of Paul's ascendant anti-Fed view keeps. Cain touts his private sector past as the CEO of Godfather's Pizza, but since leaving the company he has run for the Senate and spent three years as the head of the National Restaurant Association—an outfit that has plenty of cash with which to lobby. And worse still for this GOP economic climate, Cain was once chairman of the Kansas City Federal Reserve Bank branch.

Paul literally wrote the book on this cause—End the Fed—and he brings it up in every debate. In New Hampshire, this included a double dig at Herman Cain, first for Cain's scorn over the idea of auditing the Fed, and then for his former status as chairman of the Kansas City branch. Cain denied mocking Paul's supporters and their clamouring for an audit, and he said the prospect "doesn't bother me," but then reiterated that his "top priority is 9-9-9, jobs, jobs, jobs." Cain said later that Alan Greenspan's overseeing of the Federal Reserve "worked fine." By November, however, even Cain had come around to anti-Fed rhetoric, saying in an interview that as president he would fire Bernanke and audit the Fed.

Despite having spent more than 20 years in the House, Paul steals Cain's outsider thunder in another way: He actually is an outsider whose views don't conform to GOP orthodoxy. Paul's passion and earnestness have earned him enthusiastic-to-fanatical support and impressive "money bombs" from a broad donor base. In October, Paul unveiled a presidential plan to cut $1 trillion from the budget and eliminate "five cabinet-level departments and [begin] the draw down of American troops fighting overseas." In November, he unveiled a pithy new slogan: "Legalize freedom."

By contrast, Cain's bluntness and pleas for simplicity can sound promising to libertarian ears, but his plans to simplify government rarely get specific, particularly when he talks about foreign policy, immigration, abortion, and taxes. Cain says he's a man who will fix the country's economic woes with a 9 percent business tax, a 9 percent personal income tax, and a 9 percent sales tax, but when he focuses on government abuse, he usually just echoes Paul on issues like excessive executive power. Cain also holds some vehemently anti-libertarian positions, such as when he said the PATRIOT Act is "90 percent right on."

Paul of course has been a favorite politician among small-government fans for years—he ran as the Libertarian Party's presidential candidate in 1988—and is sometimes known as the "godfather" of the Tea Party movement. One of his breakthrough moments in this campaign came in May 2011, when, in response to a debate question about why social conservatives should vote for him, Paul ended up mocking the idea that drug laws were the only thing that prevented most people from doing heroin. The line got applause, as did New Mexico Gov. Gary Johnson's follow-up comment about the need for legalizing and regulating marijuana. But it also illustrated just how far Paul's principled libertarian views are from the GOP mainstream.

When it comes to trashing the current administration, something in which every Republican has happily engaged, Cain suggested in August that Obama should be impeached because of his order that the Department of Justice stop enforcing the Defense of Marriage Act. Paul—who also disapproved of the Obama administration's decision—instead hinted that Obama's self-proclaimed power of assassination, which he used in August on American-born suspected terrorist Anwar Al-Awlaki, was reason enough to remove him from office.

No matter what happens with Paul's campaign, libertarians, civil libertarians, and other fans of smaller government can at least be amazed and delighted that while running as a Republican, Paul criticizes the war on drugs, voices opposition to Guantanamo, advocates the complete privatization of marriage, promotes Austrian economics, and skewers the sacred cow of party loyalty in front of a national audience.

Lucy Steigerwald is an associate editor at Reason magazine.