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Comparative Government Unit 4: Party and electoral systems and citizen organizations

Electoral rules shape party systems, and interest groups connect citizens to the state in pluralist or corporatist ways.

Covers: Electoral systems, party systems, interest groups, pluralism and corporatism, social movements

Study guide

Electoral systems determine how votes become seats. In a single-member district (SMD) plurality system, also called first-past-the-post, the candidate with the most votes in each district wins, as in UK House of Commons elections. SMD systems tend to produce two dominant parties (Duverger's law) and can give a party a majority of seats without a majority of votes. In proportional representation (PR), parties win seats in proportion to their share of the vote, which encourages multiparty systems and coalitions. Mixed systems combine both: Mexico and Russia elect some legislators by SMD and some by PR. Thresholds require a minimum vote share for seats, like Russia's 5%. Nigeria's president must win a plurality nationally and at least 25% of the vote in two-thirds of the states, encouraging broad support.

Party systems vary. A one-party system allows only one party (China's Communist Party). A dominant-party system has multiple parties but one consistently wins, like Russia's United Russia or Mexico's PRI from 1929 to 2000. Two-party and multiparty systems are more competitive; in Mexico, Morena now leads. Elections in authoritarian states may be used to gain legitimacy while candidates are screened and media are controlled.

Interest groups try to influence policy. Pluralism means many independent groups compete for influence, as in the UK. Corporatism means the state recognizes a few official groups to represent major sectors like labor and business; Mexico's PRI used state corporatism, and China uses it today. Authoritarian states may use co-optation, bringing potential opponents into the system with benefits, and patron-clientelism, trading favors for loyalty. Social movements and protests push for change, sometimes with success and sometimes facing repression.

Independent election commissions register voters and candidates, run elections and certify results. Examples include the UK's Electoral Commission, Mexico's National Electoral Institute (INE, formerly IFE, made independent in the 1990s, which helped make the 2000 turnover possible) and Nigeria's INEC. Russia's Central Election Commission and Iran's Guardian Council also oversee elections, but they serve the regime, which uses them to look legitimate while controlling who can run. Nigeria's main parties are the All Progressives Congress (APC), in power since 2015, and the People's Democratic Party (PDP), which dominated from 1999 to 2015. National Assembly members are elected in single-member districts by plurality. Tinubu won the 2023 presidency with about 37% of the vote.

Mexico's Chamber of Deputies has 300 single-member seats and 200 PR seats. After the PRI lost its majority in 1997 and the presidency to Vicente Fox (PAN) in 2000, Mexico became multiparty. Morena, founded by López Obrador, won in 2018 and 2024, when Claudia Sheinbaum became Mexico's first woman president. In March 2026, Sheinbaum's plan to cut PR seats failed for lack of a two-thirds vote. Russia elects half of its 450 Duma deputies by party list (5% threshold) and half in single-member districts. In September 2026, United Russia won 349 seats, keeping a constitutional supermajority. Four other parties that rarely oppose the Kremlin split most of the rest.

In the 2024 UK election, Labour won nearly two-thirds of Commons seats (411 of 650) with roughly a third of the vote. Reform UK won about 14% of the vote but only 5 seats. This is a clear example of how first-past-the-post rewards concentrated support and penalizes spread-out support. Social movements are loose, broad efforts to change policy or society from outside government through protest, awareness and pressure. Political parties are organized to win elections and hold office. Movements sometimes turn into parties or are absorbed by them, as Morena did with anti-establishment discontent in Mexico.

Key ideas

• SMD plurality systems favor two dominant parties.
• Proportional representation encourages multiparty systems.
• Mexico and Russia use mixed electoral systems.
• Dominant-party systems hold elections but one party always wins.
• Pluralism lets groups compete; corporatism gives a few groups official status.

Formulas and rules

Common mistakes

• Thinking PR systems produce two parties; they usually produce many.
• Confusing pluralism (competition) with corporatism (state-recognized groups).

Words to know

Electoral system

Rules for turning votes into seats.

Single-member district (SMD)

One representative per district, chosen by plurality.

First-past-the-post

Plurality voting where the top vote-getter wins.

Proportional representation

Seats divided by each party's vote share.

Mixed electoral system

A combination of SMD and PR.

Threshold

The minimum vote share needed to win PR seats.

Duverger's law

SMD systems tend to produce two-party systems.

One-party system

Only one party is allowed.

Dominant-party system

Multiple parties exist but one always wins.

PRI

Party that dominated Mexico from 1929 to 2000.

United Russia

Russia's dominant party, aligned with Putin.

Interest group

An organization that tries to influence policy.

Pluralism

Many groups compete freely for influence.

Corporatism

The state recognizes a few groups to represent sectors.

Co-optation

Bringing potential opponents into the system with benefits.

Patron-clientelism

Trading favors and resources for political loyalty.

Sample practice questions

5 more questions like these, from level 1 to 5, are in the practice set.