I don't get why you discard the word forces so easily.
What about the 4.4 in Lexico, the dictionary that you mentioned?
A group of people brought together and organized for a particular activity.
Such activity may be making America great again or supporting medicare for all, for example. A specific party and its supporters, or even a faction (as suggested by Katy) inside a party, can be described as a force.
In some of the examples provided in the linked page, you can find a "political context"
In reality, it brought together some of the world's most socially conservative religious forces
You haven't shown us the full context, the sentence that you want to write using the term that you're looking for. Maybe if you improve your question adding a bit of information about that, you can get a better help.