Certainly one could never vote for a presidential candidate who holds any different views than your own. Everyone knows that if the president wants to, he can instantly change the laws to reflect his personal views. If you are pro-choice, never ever ever vote for someone who is pro-life because if they are elected abortions will immediately become illegal. Conversely, if you are pro-life but vote for a pro-choice president, the day they take office there will be free abortion clinics on every corner.
It is easy to choose who to vote for. Just choose the person who says the most pleasing things, the things that disturb you the least.