Exactly. I've run into the argument from both republicans and democrats... that they supported Obama, even though they didn't like him at all - just because they liked the other guy less - because he's 'less evil'. Or that they voted for McCain, even though they didn't like him at all, simply because they'd rather have McCain than the other guy who's worse - Obama. The hope is to get the less evil person elected, or at least make it harder for the other person to get elected.
Point being, that confronted with two choices which are both clearly evil, even if one is less evil than the other - you should not vote for either of them, period. Don't vote at all, or protest vote - on the basis of principle - especially if it clearly won't matter how you voted, when an evil decision is being made either way.
They say - "Well, my vote doesn't really count in the grand scheme of things anyways - so why should I vote third party if it won't make them win? Either way, a republican or democrat will win - so I might as well vote for a lesser of two evils."
If it doesn't matter, then that's more of a reason *not* to vote for evil. It should make it even easier, if anything, *to support principle*.
Me - I protest vote (if the protest vote is someone I do certainly agree with) to send a clear message, and the more people that protest vote, the clearer the protest against the two evil choices are.
That being said, while not voting at all is clear legitimate on the basis of principle, I feel by not voting, it does give a sense of legitimacy to those who get selected by majority. Instead of a growing percentage taking away the vote from either Rs or Ds, their percentage is greater. A greater third party vote would send a much clearer message than no vote at all.
Hell, in the example above, if I were to vote, I'd probably write in the President's name, or 'the government', or whatever.