The “lesser” fascist is still a fascist, and fascists spend much more of their time attacking us than attacking each other, and on top of that even if they do attack each other it’s through attacking us.

But the Democrats aren't fascists, lesser or otherwise. They're not 'the Republicans, but less so'; they're a different organisation with different histories and philosophies, different people and different priorities. The Democrats, for example, are not promising to overthrow the constitution, but overthrow it a bit less than the Republicans; they're not planning to overthrow it at all. Degrees of evil are not possible in this case, nor in many others. The Republicans are straight up wrong in a way that the Democrats just are not.

For these reasons, I don't buy the framing of lesser evil at all. If I did buy that framing, I would still wholeheartedly vote for the lesser evil, because it would still be better than more evil, by definition. Even your definition of 'the same amount of evil, but slower', would be better.