Republican Senator Rand Paul, from Kentucky, yesterday announced he is running for the GOP’s presidential nomination. Paul’s declaration, all at once, surprised no one, inspired supporters, and sprouted doubters.

Unlike the other lightly experienced Senators–Ted Cruz, who announced recently, and Marco Rubio, who will announce soon–Paul is both weighted down and buoyed by association. His father, Ron Paul, the perennial presidential candidate, brought a hard-edged libertarianism into the GOP, generally against the party’s will. That philosophical core defines Rand Paul uniquely and it is his greatest strength. Paul hopes that his scaled down, sometimes anti-government approach to things like surveillance, the drug war, and international affairs, could attract younger voters and provide the party with clean reasons for shrinking government’s footprint.

His libertarianism is also his greatest weakness. Like it or not, as Reihan Salam notes, Republicans just aren’t that libertarian. Not only have they favored a more muscular foreign policy, they have an ambiguous relationship with federal entitlements and they are not immune from a class-based approach to taxation.

Ramesh Ponnuru, one of the sharpest conservatives writing today, believes that Paul’s goal of transforming the Republican Party into his own image is bound to fail. Not only are parties unwieldy and resistant to change, but change works both ways. “The closer he gets to the presidency,” Ponnuru suggests acidly, “the less libertarian (Paul) gets.”

Unlike his father, Rand Paul has at least an outside chance of winning the nomination. Also unlike his father, the younger Paul seems willing to bend his philosophy toward a context that resists rigidity. Paul embraced the use of military force against ISIS, for instance, and he is working for a dramatic increase in defense spending. This tempered libertariansm, though electorally laudable, may actually cost Paul support among his ardent loyalists who don’t suffer impurities lightly. Such is the electoral puzzle that confronts Rand Paul.

Paul is an active and devout Christian. A southern politician with a religious background should be an easy sell to primary voters in Iowa and South Carolina. Paul’s libertarianism complicates this relationship. Though religious conservatives might generally favor smaller government, they also have an ingrained belief in what government can accomplish on moral matters. Though Paul views gay marriage as a state issue, how he handles other moral issues (drugs and prostitution) may be just as critical for evangelicals.