There are those I disagree with, and those I consider enemies. I have no trouble working with people I disagree with but who want the same thing, the common good. But enemies, those wish to harm or dominate others, no.
My enemy and I may have a common enemy, but once that other is eliminated, my ally of convenience will turn on me, all the stronger for not having to fight two fronts.
In this case, I would rather ally with a centrist against the far right. But that’s me.