The only way that can conceivably happen is if one does not even vote. That is "throwing a vote away", in other words, discarding it.
To actually use it to vote for a slate of Electors representative a qualified party, is not "throwing" anything away.
It is just a legitmate vote that will be counted as one for the Democrats (D) this year as for the Republicans (D) this year.
Men who died on Mt. Surabachi did so just as much to secure my American right to vote for the IAP, or AIP, or Libertarians as GOP and Democrat.
I think you should be very carefuly when you talk about "throwing a vote away", because this is a subjective value judgement.
If we care too, we could actually rationalize that, considering the government one is going to get, voting for Obama or McCain is likewise "throwing one's vote away".
But I will not go there.
I do know I will be voting FOR somebody and FOR principles, not voting in fear against anyone.
Have you read the endless posts here advising one and all that the poster will not vote? Not for McCain, not for Obama, nor for Barr, not for Nader and not for McKinney.
Voting for other than the R or D can be termed a “protest vote” as it will count for naught. That’s fine, it’s your right. Not much different than voting R in California or D in Alabama, I suppose.
Still, after the 2000 election, one should think long and hard about not voting or casting a protest vote.
Sometimes life is tough and we have to choose between the lesser of two evils.
Until you or I run for POTUS, there just won’t be a perfect canddiate.