I don't think most people feel this way, but I think there's a substantial number of people, a very large minority of both men and women, who would rather see a man continue to be president than to elect a woman.
Maybe when people see a woman they have a hard time thinking "presidential" because they've never seen an example of a strong female leader like that except in other countries.
There are a lot of people who just won't vote for a woman. To most people, this might not make much of a difference, but in a tight election, where every vote counts, then I do think it could change the outcome.
So before we throw our support behind any female candidates, we need to make sure that they are very strong in other ways as far as electability, being qualified, etc.