Rant Concerning a Romney Ad

I have tried to avoid discussing politics on this blog (I have another blog dedicated to my musings on politics), and have largely refrained from inflicting upon my political rants upon you.
So I apologize in advance from this piece, but I need to say this somewhere.

I recently saw this ad from Mitt Romney's campaign.

This was my reaction to the ad. (WARNING: Mild profanity alert.)

It's not that I don't understand the logic of this ad. From a political standpoint, it changes nothing. Every careful watcher of this presidential campaign already knew that Romney supported abortion in cases of rape and incest.
And I understand the logic behind Romney's decision to air the ad. Romney wishes to blunt the idiotic "war on women" nonsense that the Obama campaign has accused him of. He also has adopted the common political tactic of "running to the center," which involves seeking to get moderates to vote for him and emphasizing his "centrist" political positions. He seeks to emphasize positions that appeal to "moderate" voters, since he figures that his base will vote for him anyway.
I must state right away that my opinion of Romney as a candidate remains unchanged by his choice to run this ad; I will still vote for Romney this November.

And yet, the ad still bothers me immensely, for two reasons. 

The first problem with this ad is a political one: in a base election (and in this polarized America, this is an election where candidates increasingly rely on their base), why on earth would you advertise to your supporters that you support abortion, even in some cases? I can already picture individuals (Mark Shea comes to mind) already opposed to Romney seizing upon this ad to argue that Romney is simply another Obama, and convincing others to do the same. I can also picture devoted pro-lifers being so turned off by the fact that Romney supports any abortions whatsoever that they refuse to vote.
But the second objection is far more important, for it is moral in nature. For if the fetus in the womb is really a child, then a voter or politician must oppose abortion in all cases. ALL CASES. Nothing justifies the murder of an innocent victim - not even the horror of rape.
For Mitt Romney to advertise that abortion is acceptable in cases of rape and incest is for him to advertise that he is not truly pro-life. He does not hold that the child in the womb is truly a human worth protecting in all cases.
And this bothers me immensely. Where is the candidate who will say that ALL life is sacred and must be protected, no matter the cost?
I will still vote for Mitt Romney because I disapprove of Obama's evil policies. But I do so with a very heavy heart.