“[T]hird-party leaders in the United States must look for success in terms different from those that apply to the major parties, for in those terms third parties always fail. No third party has ever won possession of the government or replaced one of the major parties. (Even the Republican Party came into existence as a new major party, created out of sections of the old ones, not as a third party grown to major-party strength.) Third parties have often played an important role in our politics, but it is different in kind from the role of governing parties. Major parties have lived more for patronage than for principles; their goal has been to bind together a sufficiently large coalition of diverse interests to get into power; and once in power, to arrange sufficiently satisfactory compromises of interests to remain there. Minor parties have been attached to some special idea or interest, and they have generally expressed their positions through firm and identifiable programs and principles. Their function has not been to win or govern, but to agitate, educate, generate new ideas, and supply the dynamic element in our political life. When a third party’s demands become popular enough, they are appropriated by one or both of the major parties and the third party disappears. Third parties are like bees: once they have stung, they die.”
Pulled from chapter three of The Age of Reform by Richard Hofstadter.