Democrat Donkey and Republican Elephant smiling and happily drinking beer together, and the following words: "Oligarchy poorly disguised as a dysfunctional duopoly! Backstage, they're one rich happy family."

Well said. Only minor rewording I'd make is the following:
"Democrats won't (versus can't) stop them.
And below meme perfectly captures Dems & GOP.
#DemsAreGOP #DemsAreRepublicans
#DemocratsandRepublicansBothSuck
#DemsandGOPAreOneBigHappyFamily