How are political parties and interest groups similar and different?

Political parties and interest groups are similar in one important way. That is that they both attempt to get political candidates elected. Political parties choose candidates for office through a primary voting process in which members vote for the one they support. This is true at almost every level of government. Once the party chooses its candidates, it supports them with money, provides exposure, and provides the legitimacy that party candidacy entails. The fact that it is so difficult for third party or independent candidates to get elected in the United States demonstrates how effective they are in this process. Interest groups, on the other hand, usually represent a certain issue, or "interest." They support candidates who take acceptable positions on whatever issue or group they are organized around. Like political parties, they provide financial support through donations but especially through advertising for candidates they back. One major difference between special interest groups and political parties is that parties are best described as coalitions of many different groups of people. While parties generally share an ideological perspective, they take positions on a number of issues, called a platform. On the other hand, interest groups generally represent a single group (such as retired people or gun owners) or a single issue (like abortion rights). Interest groups, while extraordinarily powerful, do not have the kind of structural influence over American politics that parties do.