Why are *some* people who are no more supportive of abortion than I am who are pro-choice?

Regardless of where they stand on the legality of abortion many people think it is wrong, my question is to those who think it is wrong but still are or say they are Pro-Choice. I have never understood how a person can be totally against something on a moral and/or ethical level and still support the legality of said practice. That's like saying it's wrong but if somebody else decides to do it it is somehow not wrong. Help me understand how that makes any sense at all...