I think part of the problem with abortion is the left argues that "it is not a life" which is generally a weak argument. It's better to accept/concede that you are ending life, but doing so without suffering before there's a neural net that can recognize anything - I think that's the important bit (and why third trimester abortions are banned anyway).
The push back then tends to be that life itself is sacred and can never be ended (suffering is not relevant), but this is generally not truly believed by the people making the argument so it's easy to point out their contradictory support for the death penalty. They then usually say there's a difference between innocent life and people who've committed crimes at which point you're back to negotiating conditions and suffering seems like a pretty good condition to use.
[Edit] It's also a messier issue because I think a component of the debate is shaming women for sex. That they should be forced to have their baby as some sort of penance for having sex. Obviously this is largely unsaid in favor of more palatable arguments, but if it's the true driver then it's hard to even start because you're not addressing the true motivation (which may not even be fully realized by the person arguing).