I should add:
In general, with moral issues and societal issues (abortion, euthanasia, LGBTQ issues, etc.) the Republican Party is better aligned with Catholic principles.
When it comes down to certain other issues, especially financial, welfare, and justice (things like foodstamps, immigration, welfare, Social Security, Medicaid/Medicare, prison reform, opposition to capital punishment) the Democratic Party aligns better with Catholic principles.
Other issues, like the military, it really is a situation by situation basis to see which party aligns better with the Church.
I would tend to think of the Democratic Party as being, overall, closer to Catholic social teaching as a whole, and traditionally American Catholics were Democrats.
A LOT of Catholics left the Democratic Party for the GOP however in the 1970’s in the wake of Roe v Wade because the GOP opposed it, and for many Catholics, politically nothing is more important than the issue of abortion.
It seems to me though the pendulum is swinging again and many Catholics now are either Independent, third party, or Democrat, so as to render those who are Republican a definite minority.
I am personally an Independent, and in 2016 I voted for a third party for President, a Republican for Governor, several Democrats and Republicans for other positions, and one Independent and one Libertarian.