Corker--why not admit the change and move on?

I'm kind of surprised that this Chattanooga radio station is being so forthright in challenging Bob Corker's flat assertion that he is pro-life in paid radio ads, but it seems to me that Corker should just admit that he has changed his position on abortion since he ran to the Left of Bill Frist in '94. I, for one, will be hard to convince, but at least I won't be insulted.