If you are confronted with two evils, thus the argument runs, it is your duty to opt for the lesser one, whereas it is irresponsible to refuse to choose altogether. Those who denounce the moral fallacy of this argument are usually accused of a germ-proof moralism which is alien to political circumstances, of being unwilling to dirty their hands. … The weakness of the argument has always been that those who choose the lesser evil forget very quickly that they chose evil.
-Hannah Arendt, “Personal Responsibility Under Dictatorship,” in Responsibility and Judgment, 2003.
Absolutely! Not voting IS a vote and voting for a (supposedly) hopeless third party option is even more so.