Once upon a time, the Church said, “You *may*, if you find a proportional reason to do so, vote for the lesser of two evils as one possible strategy for limiting the greater evil, just so long as you are not voting for them *because* of the evil they espouse. You don’t have to but you you *may*.”
Somehow, that got transmogrified by countless members of the Thing that Used to be Conservatism into “YOU MUST VOTE FOR THE LESSER OF TWO EVILS AND IF YOU DON’T YOU ARE REALLY VOTING FOR THE OTHER GUY AND THE BLOOD OF MILLIONS IS ON YOUR SOUL IF YOU DON’T STOP TALKING ABOUT YOUR STUPID CONSCIENCE, SHUT UP, AND GET ON BOARD!!!”
This is another example of how human tradition winds up becoming dogma where the Church, at best, calls us to exercise prudence and leave others to their liberty of conscience.