Tankies tend to get really pissy about the idea of any sort of compromise

Meanwhile

Every proletarian—as a result of the conditions of the mass struggle and the acute intensification of class antagonisms he lives among—sees the difference between a compromise enforced by objective conditions (such as lack of strike funds, no outside support, starvation and exhaustion)—a compromise which in no way minimises the revolutionary devotion and readiness to carry on the struggle on the part of the workers who have agreed to such a compromise—and, on the other hand, a compromise by traitors who try to ascribe to objective causes their self-interest (strike-breakers also enter into “compromises”!), their cowardice, desire to toady to the capitalists, and readiness to yield to intimidation, sometimes to persuasion, sometimes to sops, and sometimes to flattery from the capitalists.

Naturally, there are individual cases of exceptional difficulty and complexity, when the greatest efforts are necessary for a proper assessment of the actual character of this or that “compromise”, just as there are cases of homicide when it is by no means easy to establish whether the homicide was fully justified and even necessary (as, for example, legitimate self-defence), or due to unpardonable negligence, or even to a cunningly executed perfidious plan. Of course, in politics, where it is sometimes a matter of extremely complex relations—national and international—between classes and parties, very many cases will arise that will be much more difficult than the question of a legitimate “compromise” in a strike or a treacherous “compromise” by a strike-breaker, treacherous leader, etc. It would be absurd to formulate a recipe or general rule (“No compromises!”) to suit all cases. One must use one’s own brains and be able to find one’s bearings in each particular instance.

I think Lenin would have have agreed not to vote for Biden, by the way. There's a difference between participating in a reactionary government through a revolutionary party and participating in a reactionary government through supporting its own reactionary parties.