Here is a valid syllogism; if the two premises are true, then the conclusion is true:
Most Democratic candidates are pro-abortion.
You should not vote for a pro-abortion candidate.
Therefore, you should not vote for most Democratic candidates.
Catholic bishops are getting increasingly explicit in their teachings that one or another form of the minor premise -- "you should not vote for a pro-abortion candidate" -- is true, and many lay Catholics are responding in anger to the implication that the conclusion -- "you should not vote for most Democratic candidates" -- is true.
They are right to be angry. It should not be true that you shouldn't vote for most Democrats.
What doesn't make sense to me is why they're angry at the bishops, for teaching that the minor premise is true, and not (as far as I can tell) particularly angry at a major political party for teaching that abortion is a public good. I can't think of a flattering explanation for the selective indignation.