Again, look at what I actually said. If there are only two candidates that have a realistic chance of winning, then the logical course is to vote for the one who is closest to your position of the two. Why? Because that gives you the most influence in actually implementing policies that you want.
Consider it this way. Look at the chart I've created below.
Candidate | Chance of Winning | Agreement |
A | 55% | 30% |
B | 45% | 50% |
C | 0% | 100% |
If you do the math, with Candidate A, you get a 16.5% chance that some policies you agree with will be implemented. With Candidate B, you get a 22.5% chance. With Candidate C, however, you get a 0% chance. Why? Because no matter how much you agree with the candidate, they can't implement your preferred policies unless they get elected. In that case, the rational choice is to vote for candidate B, because it gives you the greatest probability of getting policies you support. (All numbers given are just for illustration purposes.)
While I would prefer Romney win, in this sort of discussion I am more concerned with the lack of rational evaluation of the candidates that I see. If you do your evaluation and think that Obama gives you the better chance of getting your preferred policies actually implemented, then go ahead and vote for him. Unlike some other people, I have enough faith in the system that I don't believe any single person, even holding the office of President of the United States, can destroy our nation. And if a greater part of the population consistently choose elected officials who do take our nation down that sort of path, then we get the government that we deserve.
Then use those issues to evaluate the candidates and find the one that gives you the best chance of getting as much of what you want as you can. The only thing I can promise you is that voting for a person who mathematically cannot get elected will never get you want you want.