Surely because it’s forbidden to join with the wicked? Or because of a problem of too much reliance on human effort?

Is one obligated to vote?

Search here on the site for the categorical imperative. I explained that according to the imperative there is an obligation to vote, but of course that is only if you have someone worth voting for.

What about “do not form separate factions”?

Elections are a fraud. And anyone who takes part in the election celebration is basically a partner in the fraud and the deception.

According to the categorical imperative, which is idolatry, one is obligated to vote, and therefore it is forbidden to vote.

Y.D., I didn’t understand the comment.

Does the existence of different parties involve “do not form separate factions”?

Are you seriously asking whether it is permitted to hold different views and act on their behalf? Did the House of Shammai and the House of Hillel, Abaye and Rava, Maimonides and the Raavad violate “do not form separate factions”?
Right now I’m thinking that the opposite is true: the prohibition can apply only in a situation where there are no actual differences of opinion, just a meaningless split. When there are different views, then of course one should argue and fight for them.
And perhaps your question is based on the fact that there really aren’t any different views among the parties. They’re all more or less the same thing, and the struggle is mainly personal and about positions and power. That’s true, but even a struggle over power is legitimate. It’s just preferable to be honest and present it as such, and not dress it up in the finery of views and ideologies.