I'm surprised that I didn't hear anyone cite "Better the devil you know than the devil you don't" about the last presidential election. It was certainly one of the major themes.
You hear plenty of slogans and phrases encapsulating some political or social ideas, but that's not quite the same thing. The slogans anticipate, while the proverbs react to, classes of situations. For example "The people united will never be defeated" is an aspirational slogan (and piano composition): history is chock-a-block with counterexamples and compromises that only vaguely resemble victory. "He who slaughters a beast does not hesitate about skinning it," on the other hand, warns the wishful thinkers in every age. We hear "Liberty, Equality, Fraternity," or "no justice, no peace"--both aspirational (since the latter implies that there will be peace once there is justice). But "A camel never sees its own hump." You know people like that.
I like this one. Albanian: "Fire, water and government know nothing of mercy." And this "A benevolent man should allow a few faults in himself to keep his friends in countenance."