While the term interest group is not mentioned in the U.S. Constitution, the framers were aware that individuals would band together in an attempt to use government in their favor. In Federalist No. 10, James Madison warned of the dangers of “factions,” minorities who would organize around issues they felt strongly about, possibly to the detriment of the majority. But Madison believed limiting these factions was worse than facing the evils they might produce, because such limitations would violate individual freedoms. Instead, the natural way to control factions was to let them flourish and compete against each other. The sheer number of interests in the United States suggests that many have, indeed, flourished. They compete with similar groups for membership, and with opponents for access to decision-makers. Some people suggest there may be too many interests in the United States. Others argue that some have gained a disproportionate amount of influence over public policy, whereas many others are underrepresented.
Madison’s definition of factions can apply to both interest groups and political parties. But unlike political parties, interest groups do not function primarily to elect candidates under a certain party label or to directly control the operation of the government. Political parties in the United States are generally much broader coalitions that represent a significant proportion of citizens. In the American two-party system, the Democratic and Republican Parties spread relatively wide nets to try to encompass large segments of the population. In contrast, while interest groups may support or oppose political candidates, their goals are usually more issue-specific and narrowly focused on areas like taxes, the environment, and gun rights or gun control, or their membership is limited to specific professions. They may represent interests ranging from well-known organizations, such as the Sierra Club, IBM, or the American Lung Association, to obscure ones, such as the North Carolina Gamefowl Breeders Association. Thus, with some notable exceptions, specific interest groups have much more limited membership than do political parties.
Political parties and interest groups both work together and compete for influence, although in different ways. While interest group activity often transcends party lines, many interests are perceived as being more supportive of one party than the other. The American Conservative Union, Citizens United, the National Rifle Association, and National Right to Life are more likely to have relationships with Republican lawmakers than with Democratic ones. Americans for Democratic Action, Moveon.org, and the Democratic Governors Association all have stronger relationships with the Democratic Party. Parties and interest groups do compete with each other, however, often for influence. At the state level, we typically observe an inverse relationship between them in terms of power. Interest groups tend to have greater influence in states where political parties are comparatively weaker.