Frist and stem cells

I have to say I'm a bit puzzled by Senator Frist's recent decision to back expanded federal funding for human embryonic stem cell research*. I mean, obviously, it's great, but I have to wonder why he's had a change of heart. I'd reject out of hand the idea that he's generally more sensible than the rest of the religious right because he's a doctor, given his disgraceful behavior during the Terri Schiavo fiasco.

The consensus interpretation on Frist's behavior over the last year or so has been that he is positioning himself for a 2008 presidential nomination, for which he needs the crucial support of the religious right. This decision will kill (or has already killed) that support, and he can't win the nomination on the votes of moderate Republicans (McCain taught us that in 2000). So, it could be that he's decided he doesn't want to run for president, after all, so he no longer needs to grovel before the religious right. That's the only plausible interpretation I can come up with - does anyone else have thoughts?

*Just to be clear, because this topic generates a lot of confusion: Human embryonic stem cell research is currently legal and is funded at by the federal government, states, and privates sources. However, federal funding is limited to research on human embryonic stem cell lines that were created after August 9, 2001, the idea being that federal money isn't being spent on the actual destruction of embryos. The new bill would loosen this restriction by allowing federal money to be spent on creating new human ESC lines from leftover embryos from IVF (thus destroying those embryos) that are already scheduled for destruction by the parents anyway.