Thanks for the citations. It's clear that end justifies the means and lesser evil have always been rejected by Catholics. That's a great tragedy that most of the Trad clergy are throwing around the term "lesser evil" as if it were somehow a valid principle.
Now, you're going to the right of where I was, and it actually has me pondering things, whether we can cooperate in evil PRINCIPLES, and not just evil practical effects.
I've been arguing for the liceity of applying double effect, but you do raise a good question. There's something that stinks about merely avoiding cooperation in evil due to the PRACTICAL effects (counting the numbers of innocent lives lost vs. those saved, for instance).
What if we had a candidate, for instance, that wanted to put a blasphemous denunciation of God and Our Lord into the constitution or enact it as law. He might be anti abortion, anti birth control, etc. etc. ... but then we would participate in his evil principles for the practice effect of saving lives? God instructed the Israelites to completely wipe out certain groups that were practicing idolatry, and the early Christian considered it a grave evil to even drop the token grain of incense before the emperor, and then there was a serious debate about whether the Church would ever re-admit those who had compromised by doing so (even if not "meaning"/"intending" the evil, but just to save their lives).
I'll have to ponder whether or not I was wrong in applying double effect to voting. While I've been repeating the principles I've learned regarding double effect, and there are some real world applications where it applies, there's something that doesn't sit right with me about voting for any candidate that somehow represents evil principles (regardless of any calculation regarding practical effect).