All of those groups you mentioned have been pro-abortion rights or neutral in the past and have only really seen shifts in the very recent terms- the majority of opposition then and now has come from conservative white evangelicals. A more likely reason is that Democrats are unwilling to do much that smacks of controversy, as the very idea of having opinions worth fighting for is terrifying to the current crop of brand-oriented politicians.
Invited by the new age, the elegant Sailor Neptune!
I mean, how often am I to enter a game of riddles with the author, where they challenge me with some strange and confusing and distracting device, and I'm supposed to unravel it and go "I SEE WHAT YOU DID THERE" and take great personal satisfaction and pride in our mutual cleverness?
- The Handle, from the TVTropes Forums