The columnist you linked has it wrong.
Can you show me where Fred Thompson has ever called himself anything but pro-choice?
When he was a Senator, and when he ran for office, every news article you can find calls him "pro-choice."
Or has he pulled a Romney?
You'll have to forgive me; I don't believe a word you say.
I'd believe Bill Clinton before I'd believe you; at the very least, he can be charming.
We'll have to hear it from his lips. The last statement that seems to have a direct source to Thompson was from the 1994 campaign. His votes in congress were all identical to the pro-life position on those issues, so whatver he "considered" himself on the matter, he voted correctly. But that doesn't substitute for knowing his real position, to be sure.
I'm not opposed to people who change from pro-choice to pro-life. I find a lot of people call themselves "pro-choice" before they have to make any decisions regarding the issue, but what they do when confronted with a REAL CHOICE is what counts to me.
That's why I believe Romney when he says his work on the embryonic stem cell issue led him to a strong pro-life stance -- because it makes sense to me, that focusing on the issue would lead you to understand that abortion is murder, whereas if you don't have to think about it, if you never have an abortion or have a family member do it or really have to make a choice about it, you might just find saying you are "pro-choice" feels better.