Put it this way - the Church is about doing the Will of God and saving souls. The “folly of God is wiser than the wisdom of men” (paraphrased from one of St. Paul’s epistles - probably Romans, but I can’t remember which one at this time). Secondly, being pro-life and caring for social justice are not contradictory - on the contrary, they are two sides of the same coin: respecting the dignity of all human life - protecting it when it is endangered and lifting it up when it is downtrodden. All real work in social justice is inherently pro-life, and all real pro-life work is inherently socially just. There cannot be any contradiction between the two.
What good are food stamps if the people who would receive them are killed before they have the chance to live? At the same time, though, should we allow people who have already been born to starve because they cannot afford food to eat? Why are we to be pro-life, and why are we to care about the poor? Is it not because all humanity has been created in the image of God? Or are we to jettison our care for the poor due to it not meeting “Conservative” ideology or our pro-life message due to it not meeting “Liberal” ideology? How much higher are God’s thoughts than our thoughts and God’s ways above our own ways (c.f. the book of Isaiah).
The reason why the Church does not get into partisan ideological battles is due to the fact that neither side - Conservative or Liberal - is in full alignment with the ways of God. The Parties are creations of men (and women), and as such are led by the folly of humanity. The Church, on the other hand, is the creation of God the Son, directed by God the Holy Spirit, with the mission that all can be with God the Father. As such, we are called to find a way to align the ways of men (politics & public policy) with the ways of God.