Libertarianism is suddenly in fashion. Denouncing the NSA, Rand Paul draws cheers both from young leftists in Berkeley and young conservatives in D.C.—and narrowly leads in early polls for the 2016 presidential nomination. The Koch brothers—who once bankrolled the Libertarian Party—plan to spend whatever it takes to elect anti-tax, anti-regulation Republicans. Same-sex marriage and the legalization of weed continue to gain support among the public and in the courts, while a majority of Americans recoil from a law that requires them to buy health insurance. Is a nation founded, in part, to defend individual freedom now ready to embrace politicians who will rigorously apply that principle to every significant matter of state?

Libertarianism may be on the rise, but it has no real chance of taking over the Republican Party, much less the nation. A daunting set of obstacles lies in the path of true believers who would shrink the government down to Gilded Age dimensions.

The most obvious hurdle is that Americans may dislike “big government,” but they cherish their federal benefits. The libertarian charge, made most recently by Paul Ryan, that entitlement programs harm the people they are supposed to help speaks to few recipients of Social Security or Medicare (even elderly Tea Partiers), much less to anyone cashing an unemployment check or being cared for at a VA hospital. And even most Republican businessmen would resist stripping away tax credits for homeowners and subsidies for energy and agriculture—just to name some of the biggest examples of “corporate welfare.”

Second, it’s one thing to rile against an agency that monitors your phone calls but quite another to advocate, as authentic libertarians do, the demolition of the "national security" state first established during World War II and expanded after the attacks of September 11. If Rand Paul bases his presidential hopes, in part, on scaling back the powers of intelligence agencies and bringing the U.S. military back home, GOP heavies like McCain, Graham, and Rubio—backed up by millions of servicemen and women, past and present—will be glad to dash them.

Third, any Republican who promotes a coherent libertarian agenda will have to do battle with Christian conservatives—still the party’s largest and most faithful constituency and one whose definition of “freedom” excludes abortion rights and gay marriage. Paul understands this, of course; he is careful to declare he is “100 percent pro-life,” and he opposed the recent decision by a federal judge who ordered Kentucky to recognize same-sex unions from other states. But if he emphasized such views, he would destroy his image as an apostle of untrammeled liberty, particularly among the young people who rallied to his father’s candidacy. So, in early primary states like Iowa and South Carolina, Paul will have to straddle the social issues or avoid them. Most Republican voters who seek a fierce defender of “family values” will probably look elsewhere.