Party & Electoral Systems

What this unit covers

The topics below follow the published Comp Gov course framework for Unit 4. This unit is worth 13–18% of the exam, so budget your time against that rather than against how long the unit takes to teach.

Lessons in this unit

• Electoral Systems15 min · 3 objectivesDistinguish first-past-the-post, proportional representation, and mixed systems · Explain how electoral rules shape the number of parties · Identify the electoral systems used across the core countries
• Party Systems14 min · 3 objectivesDistinguish one-party, dominant-party, two-party, and multiparty systems · Classify the party systems of the core countries · Explain how party systems relate to electoral rules and regime type
• Voting Behavior & Interest Groups13 min · 3 objectivesIdentify factors that shape voting behavior and turnout across the core countries · Distinguish pluralist and corporatist interest-group systems · Analyze how interest groups gain influence under different regimes

Every term in Unit 4

All 27 terms we publish for Party & Electoral Systems, with definitions. Reading them through is the fastest way to find the ones you cannot define — then drill those in cram mode until you can produce them without the prompt.

Single-member district plurality

One seat per district to the highest vote-getter. Produces disproportional results and tends toward two-party competition — the mechanism behind Duverger's law.

Duverger's law

Plurality single-member districts tend to produce two-party systems, through mechanical exclusion of small parties and strategic voting by their supporters. The UK is the classic test case and its regional parties are the complication.

Proportional representation

Seats allocated in proportion to vote share. Produces multiparty legislatures and usually coalition government, and represents minorities better at the cost of clear accountability.

Electoral threshold

The minimum vote share for any seats — 5 percent in Russia, 3 percent in Mexico. Excludes small parties and, in Russia, has been used to shape which opposition can enter the Duma.

Mixed electoral systems

Combining district and proportional seats. Mexico's 300 plus 200 split and Russia's current 225 plus 225 both aim to balance local representation against proportionality.

Two-round (runoff) systems

If no candidate wins a majority, the top two contest a second round. Used for the Russian and Iranian presidencies; it manufactures a majority that a plurality system would not.

Nigeria's presidential formula

Plurality plus 25 percent in two-thirds of states, with a runoff if unmet. An electoral rule designed directly against regional fragmentation.

UK party system

Conservative and Labour dominate Westminster, with the Liberal Democrats persistently underrepresented and the SNP overrepresented relative to national vote share because its support is geographically concentrated.

Why concentration matters under SMD

A party with 5 percent spread evenly wins nothing; the same 5 percent concentrated in one region wins seats. This explains the SNP and Liberal Democrat contrast in a single sentence.

Russia's United Russia

The dominant party of power, organized around the executive rather than a program. It provides parliamentary majorities without functioning as an independent political force.

Russia's systemic opposition

Parties permitted to hold seats — the Communist Party, LDPR, A Just Russia — that do not seriously contest executive power. The category is essential to describing Russia accurately.

China's one-party system

The Communist Party permits eight minor parties within the United Front, none of which competes for power. Elections occur only at the local people's congress level.

Mexico's PRI dominance and its end

The PRI held the presidency from 1929 to 2000. Electoral reform, an autonomous electoral authority and economic crisis ended it, and 2000 marks the alternation of power.

Mexico's current party landscape

MORENA emerged from the left in the 2010s to become dominant, with the PAN and PRI diminished. Rapid realignment within a consolidated democracy.

Nigeria's party system

The PDP dominated from 1999 until the APC won the presidency in 2015 — the first opposition victory since the return to civilian rule. Parties are coalitional and ideologically thin.

Iran's factions rather than parties

Politics runs through conservative, reformist and pragmatist factions rather than durable parties, because candidate vetting rather than party competition determines who can run.

Candidate vetting as an electoral mechanism

Iran's Guardian Council disqualifies candidates before voting. Elections are competitive within a preselected field, which is why turnout and choice must be assessed separately.

Gerrymandering and malapportionment

Gerrymandering draws boundaries to advantage a party; malapportionment gives districts unequal populations. Independent boundary commissions are the UK's institutional answer.

Referendums

Direct votes on a question. The 2016 Brexit referendum and the 2014 Scottish independence referendum are the syllabus cases, and both show a legally advisory vote acquiring binding political force.

Coalition government

When no party holds a majority, parties govern together. The UK's 2010 to 2015 coalition is notable precisely because it is rare under plurality rules.

Party discipline

The reliability with which legislators vote with their party. High in the UK, where the whip system and reselection give leaders real leverage; weaker in Nigeria and Mexico.

Interest groups: pluralist vs corporatist

Pluralist systems have many competing groups with open access, as in the UK; corporatist systems grant designated groups privileged access, historically Mexico under the PRI.

State corporatism

When the state creates and controls the groups that represent society. China's official trade union is the clearest case: it is an instrument of the party, not of workers.

Clientelism and patronage

Exchanging material benefits for political support. Pervasive in Nigerian and historically Mexican politics; it substitutes personal exchange for programmatic representation.

Electoral integrity indicators

Independent administration, ballot secrecy, media access, candidate eligibility, and observer access. Comparing these one by one is more defensible than labeling an election free or unfree.

Turnout and compulsory voting

Turnout varies with the perceived stakes and the ease of voting. Compare a country's turnout to its own history rather than across countries, since the rules differ too much.

Which electoral system to recommend, and why

The essay usually asks you to defend a choice. Proportional representation for representation of a divided society; single-member districts for accountability and stable majorities. Name the trade-off explicitly.

What examiners penalize here

• Memorize the pairing: **FPTP → two parties** (UK), **PR → many parties + coalitions**, **mixed → in between** (Mexico, Russia). When a prompt changes the electoral rules, predict the party-system effect through Duverger’s law for full credit.
• Distinguish **one-party** (rivals banned — China) from **dominant-party** (rivals legal but never win — Russia, historic PRI Mexico). The presence of *legal but powerless* opposition is the giveaway for a dominant-party system.
• Contrast the two interest-group models cleanly: **pluralism** = many groups, open competition, no guaranteed access (UK); **corporatism** = few recognized groups with privileged access, and in its **state** form the government controls them (China). Name the model *and* the country.

Practice Comp Gov

Our practice bank is drawn from across the whole course rather than filtered to one unit, which is closer to how the exam asks anyway — it will not tell you which unit a question is testing.

Questions about this unit

All 5 units of AP Comparative Government & Politics

1. Unit 1 · Political Systems, Regimes & Governments
2. Unit 2 · Political Institutions
3. Unit 3 · Political Culture & Participation
4. Unit 4 · Party & Electoral Systems
5. Unit 5 · Political & Economic Changes