That's part of it. However, some leftist that I know would have voted for mccain if Sarah Palin were not his running mate. They hated her because she is anti-abortion. One person told me that her mother had an abortion long ago and voting for Palin would condemn her mother's actions. She told me she would feel guilty voting for Palin. I don't imagine the entire base on the left feel that same way, I just thought it was an interesting reason not to vote for Palin.
A response to this dodo might be to sympathize and give your condolences that her mother had not always aborted her children!