Kathryn, your correspondent is quite right here. A pro-life candidate who was previously pro-choice could be a great asset and a better sell than someone who’s been pro-life all along. Many people don’t think about the issue terribly much and, if they do, accept the Democrat-Supreme Court-media framing of the issue as one of “personal choice”. And, if you come at it from that end, the pro-life-all-along crowd can seem the ones who are doctrinaire and absolutist.
It’s entirely reasonable to have been pro-choice and to come to realize, as your reader says, that the abortion crowd just wouldn’t stop – that from a “woman’s right to choose” to partial-birth infanticide to state-funded embryo farming – isn’t a slippery slope but a dive off the cliff. To see the “individual right” of abortion as something not in the broader society’s interest is also a plausible and compelling shift, given the demographic death spiral in Russia and other parts of Europe.
Governor Romney needs to do quite a bit of work on his pitch in this field, but you shouldn’t be holding it against the guy that he’s changed his mind. If he means it, then that’s great news for us: we’re meant to be persuading people, aren’t we? And, if he’s just being opportunist, then even that is modestly encouraging.