From Scott Klusendorf's The Vanishing Pro-Life Apologist.
Put differently; is there any reasonable person in America today who would argue that while he personally opposed the enslavement of blacks, he wouldn’t oppose the legal right of his neighbor to own one if he so chose? In fact, when people tell me they personally oppose abortion but think it should be legal anyway, I ask a simple question to audit their core beliefs about the unborn. I ask why they personally oppose abortion. Nearly always, the response is, “I oppose it because it kills a baby,” at which point I merely repeat their own words. “Let me see if I’ve got this straight: You say you oppose abortion because it kills a baby, but you think it should be legal to kill babies?”
But how does a pro-life apologist answer a straightforward "yes" here. Yes, it's wrong to kill babies, yes, it's equally wrong to make laws against killing babies under these circumstances.
Does the prolife apologist have anything more than intuition here?