US Political Parties, Pressure Groups and Campaign Finance
US politics is dominated by two parties, the Democrats and the Republicans, an outcome commonly explained by the single-member plurality electoral system, which tends to squeeze out smaller parties, a pattern known as Duverger's Law.
Before you start
No specific prerequisites - this is a good place to start.
Method
- Learn why the US has a durable two-party system: single-member plurality/first-past-the-post elections (Duverger's Law), restrictive ballot access rules for minor parties, and high polling thresholds to qualify for nationally televised debates.
- Learn the difference between a sectional (or interest) pressure group, representing its own members' interests, and a promotional (or cause) group, campaigning for a cause that need not personally benefit its supporters, with a named example of each.
- Learn the main methods pressure groups use: lobbying legislators and officials, litigation (bringing test cases through the courts), grassroots mobilisation of members or the public, and campaign donations through political action committees (PACs).
- Learn named examples of factions within each major party (e.g. the Republican Party's more populist wing versus its traditional/establishment conservatives; the Democratic Party's progressive left versus its moderate/centrist wing) so you can support a claim about internal party divisions with specifics.
- For a polarisation question, weigh evidence that the parties have become more internally unified and ideologically distant (fewer split-ticket voters, more predictable party-line voting in Congress) against evidence of continued internal factionalism within each party that complicates a simple 'two unified blocs' picture.
- For a pluralism question, weigh the pluralist view that competition between many pressure groups produces balanced outcomes against the elitist view that resources (money, access, organisation) concentrate real influence with a smaller number of well-funded groups.
Worked example
Assess the extent to which the growth of party polarisation has undermined effective government in the USA.
- Define polarisation precisely: parties becoming more internally ideologically unified and more distant from each other, reducing the number of moderate, cross-party-friendly legislators.
- Build the case that polarisation undermines government: it makes bipartisan compromise harder to reach, increases the likelihood of legislative gridlock, especially under divided government, and can contribute to standoffs over routine matters such as passing a federal budget.
- Build a case that limits this effect: because the president can still use informal powers such as executive orders to act without Congress, and because both parties retain some internal diversity (moderate members willing to cross the aisle on specific issues), polarisation does not make government entirely impossible, only harder in certain areas.
- Add a further point: some scholars argue polarisation gives voters a clearer choice between genuinely distinct party platforms, which can be seen as a democratic benefit even as it makes cross-party legislative compromise harder to achieve.
- Reach a conclusion that weighs the practical cost of more frequent gridlock against the clarity-of-choice benefit, and states clearly which effect the evidence supports as dominant.
Practice questions
Try each question, then tap to reveal the answer.
Q1Name the electoral system used for almost all federal elections in the USA, and the principle that links it to a two-party system.Show answer
Answer: Single-member plurality (first-past-the-post); the principle is Duverger's Law, which predicts that plurality systems tend to produce two dominant parties.
Q2What is the difference between a sectional and a promotional pressure group?Show answer
Answer: A sectional group represents the shared interest of its own members (e.g. a trade or professional body); a promotional group campaigns for a cause that need not personally benefit its own supporters.
Q3What is a political action committee (PAC)?Show answer
Answer: An organisation that raises and spends money to support or oppose political candidates, subject to contribution limits (a Super PAC has no such spending limit provided it does not coordinate with a campaign).
Q4Give one method, other than donations, that a pressure group can use to influence policy.Show answer
Answer: Lobbying, litigation (bringing a test case through the courts), or grassroots mobilisation of members or the public.
Q5Name one faction within either major US party.Show answer
Answer: For example, the Republican Party's more populist wing, or the Democratic Party's progressive/left wing.
Q6What is meant by 'party polarisation'?Show answer
Answer: Parties becoming more internally ideologically unified and more distant from each other, reducing the overlap or common ground between them.
Q7What is the pluralist view of pressure group influence?Show answer
Answer: That competition between many different groups, none of which dominates, produces a reasonably balanced overall outcome.
Exam-style questions
Written in the style of a A Level Politics exam paper, with a full mark scheme.
Explain and analyse three methods pressure groups use to influence policy in the USA.
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Tick each line you got. Your score builds from the marks on the scheme.
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Assess the extent to which the growth of party polarisation has undermined effective government in the USA.
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Tick each line you got. Your score builds from the marks on the scheme.
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See real A Level Politics past-paper questions, with official mark schemes →
Free printable worksheet
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