Part of the problem with American liberals is that they’re consumate pushovers, allergic to effective tactics. You can get them to concede that the Democrats suck but convincing them to actually stand up to them in any way is a whole other matter.

My approach on here, (which generally doesn’t work), is to call out “lesser evilism” as an ideology rather as just “rational truth.” I’ll go into the game theory example where two people have a hundred dollars to split, the first makes an offer and the other either accepts or denies, if they deny, nobody gets anything. If both players were “rational,” then the first person would offer only $1 and the second would accept, because $1 is a “lesser evil” than $0. But in practice, most people reject offers below around $30, and as a result most offers are closer to that range. The “irrational” approach is more effective, because it’s about establishing conditions and a credible threat.

When they inevitably ignore/reject that explanation and call me a secret Trump supporter/Russian bot/red fash, I just tell them that I am irrational and unpredictable and willing to do things out of pure spite, and if they don’t want me to they’d better make sure I get what I want, or I will start executing one vote every hour on the hour. Because of they can’t be persuaded to understand basic concepts of how bargaining works, then I figure I’ll just deploy the tactics and teach by demonstration.

Though this gets back to the problem that even when they pretend to criticize the democrats to try to be more persuasive to the left, it’s generally insincere and as soon as they’re not talking to us they’ll celebrate democratic politicians full-throatedly.

Like you say, it often feels like a lost cause.