Political Parties and Interest Groups
What parties do
Parties link citizens to government, recruit candidates, mobilize voters, and organize legislatures. Party identification is the single strongest predictor of vote choice. Realignment occurs at critical elections (1800, 1860, 1896, 1932); dealignment describes weakening attachment since the 1960s.
Why two parties
The single-member, plurality district rule (Duverger's law), winner-take-all elections, and the electoral college penalize third parties, which more often act as spoilers than as winners.
Money
Buckley v. Valeo (1976) treated spending as protected speech while permitting contribution limits. The Bipartisan Campaign Reform Act (2002) banned soft money. Citizens United (2010) allowed independent expenditures by corporations and unions, producing super PACs - which may not coordinate with candidates. Disclosure rules and dark money remain contested.
Interest groups
Groups seek access, not office. They lobby, litigate, file amicus briefs, and run grassroots campaigns. Olson's free-rider problem explains why groups offer selective incentives; the revolving door and iron triangles describe insider influence, while issue networks describe looser, broader coalitions. Pluralism assumes competition offsets any single group's power; critics note that well-funded, concentrated interests organize more easily than diffuse ones.
Traps
Do not confuse parties (which nominate candidates) with interest groups (which endorse and pressure). Do not claim super PACs give money directly to candidates - they spend independently. And remember that a party's national platform is not binding on its officeholders.
Rule of thumb
If the scenario involves nominating and electing candidates, think party; if it involves influencing those already in office, think interest group.