This one comes up a lot in a lot of different forms. What's funny about this argument is that it depends on a kind of logic which the argumenter usually says he rejects. See: this person can't vote for Romney just because he's "Not Obama". Somehow, it's not enough that Mitt Romney is "not" anything like President Obama -- he needs to have some specific merits other than being "not the incumbent" to get this informed voter's vote.
But this person could vote for Reagan -- if he were alive and not ravaged by demetia. This person could vote for Ron Paul -- if he were alive and not ravaged by dementia and he had ever won the nomination by a national political party. See: things like the actual qualifications of Mitt Romney get utterly lost on people consumed with their own fantasy politics team. In their world, they have drafted Reagan, Ron Paul, Barry Goldwater, Rushdooney, Captain America and Abe Lincoln to their fantasy league roster, and they are thereafter absorbed by debates which are the adult equivalent of, "who would win in a fight -- Spiderman or Daredevil?"
The sad fact is that you can only vote for the people actually in the election. Let me rephrase that: you can write in anything you want, -- that's your legal right -- but when you are trying to take the moral high ground, you have to do more than look down your nose at people who are voting for the actual candidates rather than using the equivalent of Foxe's Book of Martyrs as the guideline for those who are sufficiently sanctified and glorified to take the oath of office.
You also have to take into consideration the role of your vote. Voting in the primaries is not the same as voting for the actual office. As I have said before, when you are voting in primaries or run-offs, you should vote as extremely as you think is necessary or possible -- and you should vote for a person actually in the run-off. You should drive the candidate selection process to the point on the political spectrum which you stand on with this simple understanding: whoever is elected is going to fail to get everything he sets out to do, and you want the person in the office to fail as close as possible to your position. Using that exact same logic -- morally, mathematically, practically, intellectually -- casting a vote for someone who is not even a choice for even 30% of the precincts voting does not drive the process to your end of the spectrum: it enables the party/candidate with the plurality-winning minority to win.
Last, but not least, let's remember that you are not voting for National Pastor: you are voting for the man who will set the executive priorities for the secular government. You cannot find a man qualified to be a pastor who is qualified for that job -- except Jesus, and he is neither running for office, nor is he in need of your vote to be King of Kings. If you make this choice as if you were conducting a pastoral search, you will not only be disappointed, I promise you: you will be deceived.