Well, for one thing "hate" is not is christian virtue. Mabe in some nice way you can tell her that? If she says you should not believe anything you read or see about him, then there is really nothing you can do. Mabe she just distrusts politicians in general? Do you know that much about her? If she is a Kerry person you could tell her about who supports him, like Planned Parenthood, The gay rights organizations, seperation of church and state people, etc.... and that you cannot link yourself with those people or with politicians who support such organizations.
I don't really know if she was a Kerry supporter or not (I'm not sure she even voted) but she sure was giving me the business for voting for (in her view) an anti senior citizen monster.