As I understand it, this isn’t like Northern Ireland, where feeling on the ground is substantially pro choice, but the political system is so toxic that an oppressive state is perpetuated.
There is a kneejerk, but also deeply held religiosity throughout America (though especially in the south) that is miles and miles away from any other western democracy that it’s hard to conceptualise. 20% of Americans go to church etc at least once a week. Almost half are identified members of a local religious community/congregation. Both those stats, btw - from 2020 data, are by far the lowest for years, but are unrecognisable in otherwise similar nations.
As of 2014, 55% of Americans across all religions and none, say that they pray every single day. Even if there’s an element of inflation in self reporting, you have a nation where 55% of people think they should pray daily.
And people vote on religious grounds. Preachers and local religious leaders tell their communities who to vote for.
There is a simple, superficially consistent case against abortion. If you believe abortion is killing a baby, and on the surface that’s not a huge leap, then of course you’ll vote against abortion rights. It must seem like a legally sanctioned Holocaust of children. And you wouldn’t allow a baby to be killed even if it was conceived through rape or incest, or if it was going to have overwhelming, life-limiting defects and would only survive for moments after birth. If you believe a fertilised, implanted egg is where a life begins then the rest is very clear. And if you are internally and performatively religious, and your religious community, elders and leaders have told you that is where life begins, and that the only morally acceptable way to vote is against abortion, then you do.
In the south, it’s not unknown for democrat candidates and politicians to have to be publicly anti abortion too.
They're rarely so "all human life is sacred" when it comes to wars, refugees, people starving, poor people's healthcare, the death penalty, etc etc though are they.