In a society where casual sex is considered normal, people want an escape valve from their reproductive mistakes, and so they are terrified to let abortion go. Women especially do not want to be compelled to birth a baby from an unwise hook-up or temporary boyfriend.
For single women, abortion is part of tribal identity. On some level, they see males as an opposite tribe that must be managed if not outright combatted. Abortion polarizes them and the rest of the Left gets in line behind it:
A Cygnal poll from this month found that 56% of respondents overall and a plurality of Democrats support a national limit on abortion after 15 weeks, a point when science proves babies in the womb can feel pain.
Today’s Democratic Party tolerates no debate on abortion. Nearly every Democrat leader will bend over backwards to avoid naming any protections they support for babies or their mothers or limits they would place on abortion. Instead of recognizing that Americans deserve clarity on the issue, Democrat pollsters urge Democrat politicians and candidates to avoid discussing milestones that humanize the child in the womb at all costs. They are caving to the louder abortion on demand activist voices.
While most Democrats may support reasonable restrictions on abortion, for them this is an issue like gun rights are to the Right: any ground given will be abused, so you ask for the absolute extreme in order to force your perspective through politics.
They portray it as a civil rights issue. Assuming that casual sex will remain the norm, for them it is about the right of women to bodily autonomy, which like other civil rights must be affirmatively granted by government:
Abortion is a necessity for women. Without it we have no ultimate control over whether, when and with whom we bring a child into this world.
More cynically speaking, this is a shadow right, that is one that protects another, and that is the right to casual sex because this is the only way to disrupt marriage, which if it is a common social goal disrupts the absolute individualism of women.
This shows us however that the Left has very little upon which to unite against the Right. They focus on issues like inequality, diversity, and abortion because our government is already so far Left, and most people so deep in the Left-leaning WW2 ideology, that they have no real gripes only symbolism.
As is the case in most warfare, it makes little sense to attack your enemy where he is strongest, especially if that in turn makes him stronger. However, the GOP sees in abortion an opportunity: it can unite the various special interests on a loser issue and take donations for next time immediately.