It has to mean, willing to let people kill unborn babies. That's what "pro choice" means in today's lexicon. Being "mildly pro choice" means, literally, "mildly" being in favor of the killing of unborn babies. Sorry, but I prefer politicians who aren't in favor of the killing of unborn babies.
As do I. But I also prefer Republican candidates vs. Democratic candicates too.
Is President Bush "willing to let people kill unborn babies" in his support of the three exceptions?