Sigh. So much to say. So little time. Will somebody please tell me why so many people on this board can't seem to differentiate between political parties and political ideology? A Libertarian, someone who is a member of the Libertarian Party, is not the same thing as a libertarian, someone who believes in limited government, the free market, et al. On the political spectrum, libertarians are conservative, so it follows that not all conservatives are Republicans, and yet people think that Republican Party = conservative thought. Jeez, some people need to get past this high school level of political thinking.
And regarding why a Libertarian has never been elected, it is for the same reason no third party candidates were elected in the 20th century. In the modern era the major political parties merely absorb the platforms of any viable third party when they become a force. That's the bad news. The good news is that third parties and alternative ideas can have an influence in shifting the ideology and make-up of the major parties, but will never get elected.
Capiche?
And, in the meantime, for the better part of the last two centuries governance of the nation has been steadily sliding to the left, or at least, away from the constitutionally limited republican form of government as established by our founders. If (libertarian/constitutionalist) third parties are having any influence, I don't see it. Would be far better in my opinion to run our most conservative candidates as Republicans where they at least stand a chance of being elected. They're bound to have more effective direct influence on legislation and policy as elected representatives than they will ever have shouting from the peanut gallery. Of course, that means they'd have to clean up there act a bit and make themselves presentable to the electorate. Refer to CONGRESSMAN Ron Paul, big (R) small (l) for example.