As more of the pro-choice Republicans see that Casey is also pro-life, Santorum regains more of those voters. The internals of a recent poll showed Santorum regained significant ground with Republicans on a second ask after they were informed Casey was also pro-life.
Very true. Pro abort RINO's in the Philly suburbs were key to electing Ed Rendell in 2002. However, if choosing between a pro-life conservative Republican and a pro-life liberal Democrat, these voters will probably stick with the Republican.