The average voter pays precious little attention to the candidates, their positions, and their votes. Some positions they don't care about. Moral issues are what they deal with all the time - stealing from the job, sleeping with the secretary (or boss), cheating on your taxes, etc. Thus, people tend to have cemented their moral values (to some extent). They have enough moral fiber to avoid doing these things (for the most part), and they expect their leaders to be at least as good as they are. 'Best and brightest' and all that.