Once upon a time Rand Paul, the junior senator from Kentucky, was seen by a number of Republican pollsters and political strategists as a viable candidate for the presidency. His unconventional brand of “get off my back” libertarianism, non-interventionist foreign policy and privacy-rights advocacy earned him the respect and admiration of college students and younger voters—precisely the constituency that the GOP has had trouble attracting during recent presidential election cycles.

Unfortunately for Paul, this popularity didn’t last long enough to carry him past the Iowa caucuses. His disappointing fifth-place finish in Iowa—a state that his father carried with 10 percent of the vote in 2008 and 21 percent in 2012—was enough to convince him that his ground game and his declining campaign war chest could not survive beyond the first-in-the-nation contest. Mega-donors like Sheldon Adelson and neoconservative commentators like Bill Kristol were always suspicious about how a President Rand Paul would run America’s foreign and national security policy. In their eyes, Paul’s foreign policy positions were at the very least dangerous and at worst cataclysmic for the country’s safety and security. His vehement opposition to the war in Iraq was just the starting point—Rand Paul was, in effect, the walking, talking, living nightmare to them.

On practically every single foreign policy issue of major consequence, Paul was pushing the opposite of what would normally be the GOP’s position. On National Security Agency surveillance, Paul broke with the likes of Senator Marco Rubio, Governor Chris Christie, former Governor Jeb Bush and most of the other Republican candidates—arguing that if America’s intelligence agencies wanted to acquire your personal information, they should go through the normal process of making their case to a judge and getting a warrant. Although Paul would eventually express his disapproval of the Iranian nuclear agreement, he was the only Republican in the Senate chamber, apart from Arizona’s Jeff Flake, who was at least open to the prospect of looking at the deal on its merits and supporting the concept that international diplomacy could, in fact, solve a problem of immense consequence.

On Syria, Paul was the only candidate on the debate stage who vocally argued against a U.S.-led no-fly zone—a policy that would inevitably lead to an escalation of U.S. military involvement and the real risk of shooting down Russian aircraft that happened to fly into the same airspace. When Chris Christie emphatically said that he would not hesitate to shoot down a Russian plane if it entered a prospective no-fly zone, Paul seemed genuinely flummoxed that the New Jersey governor would engage in an act of war that was likely to result in direct armed conflict between the United States and Russia. “I think if you're in favor of World War III, you have your candidate,” Paul said in reference to Christie.

Now that Rand Paul has dropped out of the presidential primary race, it will become increasingly difficult for Americans watching the debates to distinguish one Republican from another on the stage. Whether or not one happened to agree with Rand Paul’s policy positions on privacy, national security or terrorism, one thing is certain: he was the lone voice in the GOP primary race who was willing to buck the conventional wisdom of the party. With Paul gone, expect to witness a Republican presidential field that is far more monolithic.

Daniel R. DePetris is an analyst at Wikistrat, Inc., a geostrategic consulting firm and a freelance researcher. He has also written for CNN.com, Small Wars Journal and the Diplomat.

Image: Flickr/Gage Skidmore.