When you see a button with a red, white and blue donkey, the Democratic party likely comes to mind. In contrast, interest groups don't usually have a recognizable logo or icon. In modern democracy, political parties and interest groups play prominent roles in government. Parties and interest groups are similar in many ways: Both are organized groups of people working toward specific goals in the government and both promote politicians and raise money to accomplish those goals. Despite their similarity, however, political parties and interest groups are different organizations that serve various purposes within a country's political system.
The primary difference between a political party and an interest group is the purpose that each serves. Political parties exist to gain power over governmental policy by winning elections for political office. They do this by supporting candidates for offices and helping them win elections through advertising and fundraising. They have official opinions on a wide variety of issues, but these are subject to change. An interest group's goal is to promote a position on a specific issue such as gun control or agriculture. Interest groups do not necessarily have their members run for office, and they vote in a nonpartisan way, supporting candidates who promote their point of view.
Political parties are multi-focused and interest groups generally center their attention on one issue. For example, a political party's members generally have similar views but do not agree on every issue. Examples of this can be seen in the Republican Party with a split over support for gay marriage and in the Democratic Party with the "Blue Dog" coalition of Democrats who identify as fiscally conservative. Every four years, parties consult with their members to establish a new platform based on majority viewpoints, but their identities do not change because of a change of position. Because interest groups are formed around a single issue, they cannot change their official position without changing who they are. Members of interest groups do not necessarily have views in common outside their shared issue.
Because the defining characteristic of an interest group is its focus on a single issue, interest groups sometimes emerge within political parties. These groups work to put pressure on other members within their party and will sometimes vote against their own party to accomplish their goals. An example of this occurred during the 2000 election when some Texas Democrats voted for Ralph Nader, a member of the Green Party, because they felt that Democrat Al Gore's policy was not environmentally friendly enough.
The methods that political parties and interest groups use to accomplish their goals are often similar. Both engage in electioneering, raising money, highlighting issues and supporting candidates to influence the outcome of an election. In addition, interest groups also use lobbying, an attempt to influence a politician's decisions, as well as filing lawsuits to advance their position. Some large interest groups spend millions of dollars on lobbying each year, using money for purposes such as campaign funding. In 2012, for instance, the National Rifle Association spent $3 million dollars lobbying the federal government on gun legislation. This was in addition to the almost $19 million the NRA spent in an effort to influence the 2012 elections. Unlike parties, interest groups also rely heavily on large numbers of members to influence politicians and create change through voting. The AARP, for example, is the largest interest group in the U.S. with more than 37 million members, and it uses this influence to fight for legislation favorable to senior citizens, such as continued Social Security benefits and Medicare coverage.