Abortion is not the only moral issue to consider when you decide how to vote. You may also be concerned about education, healthcare, the distribution of wealth, the environment, foreign policy, investment in infrastructure, and so on. You may consider that on balance you are doing the better thing by voting for a pro-choice candidate whose views better align with yours on every other issue. Politics is never going to be simple.
I live in Great Britain (the situation is somewhat different in Northern Ireland), where all of the major parties take a more or less liberal stand on abortion. Over the years I’ve voted for candidates from the Labour Party, Liberal Democrats, and Green Party, and one time an independent candidate. Probably my biggest concern has tended to be foreign policy, which I know for most voters typically ranks as their least important concern. Taxation and public spending are also typically important concerns for me. When I voted for an independent (who won) it was in protest against the electoral college system used to select the candidate for the ruling party. If I wanted to vote for an anti-abortion candidate I’d have to vote for a candidate from an obscure far-right party who doesn’t stand a chance of being elected and who would also advocate all sorts of dreadful policies.
