At some point, most of us have found ourselves part of a group trying to solve a problem, like picking a restaurant or movie to attend, or completing a big project at school or work. Members of the group probably had various opinions about what should be done. Some may have even refused to help make the decision or to follow it once it had been made. Still others may have been willing to follow along but were less interested in contributing to a workable solution. Because of this disagreement, at some point, someone in the group had to find a way to make a decision, negotiate a compromise, and ultimately do the work needed for the group to accomplish its goals.
This kind of collective action problem is very common in societies, as groups and entire societies try to solve problems or distribute scarce resources. In modern U.S. politics, such problems are usually solved by two important types of organizations: interest groups and political parties. There are many interest groups, all with opinions about what should be done and a desire to influence policy. Because they are usually not officially affiliated with any political party, they generally have no trouble working with either of the major parties. But at some point, a society must find a way of taking all these opinions and turning them into solutions to real problems. That is where political parties come in. Essentially, political parties are groups of people with similar interests who work together to create and implement policies. They do this by gaining control over the government by winning elections. Party platforms guide members of Congress in drafting legislation. Parties guide proposed laws through Congress and inform party members how they should vote on important issues. Political parties also nominate candidates to run for state government, Congress, and the presidency. Finally, they coordinate political campaigns and mobilize voters.