Just wanted to provide some quick thoughts on Libertarians. They're just so funny sometimes.
The first reason they'll never have much power is because many insist on calling the purity police. To those Libertarians, Ron and Rand Paul are not "True" Libertarians. While I'll agree that neither man fits the mold of what an ideal Libertarian would look like (besides the fact that both are actually members of the Republican party, but they are Republicans who espouse Libertarian concepts), how do these Libertarians (who apparently believe they themselves are pure enough) think they'll ever have a successful political party if they won't accept people into the party for not being pure enough? That's going to limit membership (maybe this is why the Pauls are Republicans?) and, frankly, there is strength in numbers.
And now just yesterday I came across another potential pitfall. A good number of Libertarians probably don't like giving their information out to groups in the name of privacy. Would they be willing to go against this ideology for the sake of the party? Maybe. But if not, that's going to limit the party's ability to raise money and recruit volunteers if Libertarians are unwilling to give the party their contact information.