Two-party system pretty much guarantees defensive voting by informed people. Most Republicans I know hold their noses when voting got GOP. The most common positive view of McCain I heard was “He’s old, maybe he’ll die soon after the election.” Others merely thought he was less horrible than Obama, not much of an endorsement.
I suspect that plenty of well-informed voters consider a Republican president to be a greater threat. Economic reasons aside, let’s talk about privacy. While Roe-vs-Wade is an established legal precedent for personal privacy, we do have a government that violates everybody’s financial and personal privacy routinely in pursuit of the “war on drugs”. We also have a government that’s entirely willing to murder people over a couple hundred dollars of tax revenue. As John Ross pointed out, the kind of draconian enforcement necessary to effectively restrict abortions would make the USSR look benign by comparison.
So, on the one hand, we had an authoritarian socialist representing a party that is perceived as anti-gay (the vocal opponents of equitable legal treatment of gays basically tarred the rest with guilt by association) and anti-privacy (via repeal or blocking of Roe-vs-Wade). On the other hand, we have an authoritarian socialist anti-gun party with an even more harmful economic program than the first, but with less manifested intent to mistreate certain segments of the population. Those segments, along with their friends and family, might view that alternative as less immediately harmful. Most people are offended by the government efforts to stick their noses into private gun safes. How do you think people feel about equally official efforts to pry into their wombs or sniffing up their asses? And I speak in generalities here, as some members of each party would not fit the typical molds.
I view Republicans as a lesser threat: I feel that I am more likely to have necessary funds and guns with them in control of government. With lawyers, guns and money, I can resist their other bright ideas. Other people feel that Democrats are a lesser threat because of the above-mentioned factors. I can’t think of anyone from my social circle who have any enthusiasm for either, but most hold their nose and vote for the less aggressive evil as perceived at the time. That’s were this concept of a “left libertarian” comes from — someone who agrees with me on pretty much everything but gives different weight to specific concerns.
In the end, Democrats will probably continue to run around screaming for gun control and punitive taxes against anyone not on welfare, and the Republicans will shove their pet religion where it doesn’t belong, with armed enforcers of virtue jackbooting around. And the Libertarians will continue to have the organizational capabilities of autistic cats, getting the same 1% in every election.