Primary election

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Social choice and electoral systems
Social choice Mechanism design Comparative politics Comparison List (By country)
Single-winner methods Single vote - plurality methods First preference plurality (FPP) Two-round (US: Jungle primary) Partisan primary Instant-runoff UK: Alternative vote (AV) US: Ranked-choice (RCV) Condorcet methods Condorcet-IRV Round-robin voting Minimax Schulze Ranked pairs Maximal lottery Positional voting Plurality (el. IRV) Borda count (el. Baldwin) Antiplurality (el. Coombs) Cardinal voting Score voting Approval voting Majority judgment STAR voting
Proportional representation Party-list Apportionment Highest averages Largest remainders National remnant Biproportional List type Closed list Open list Panachage List-free PR Localized list Quota-remainder methods Hare STV Schulze STV CPO-STV Quota Borda Approval-based committees Thiele's method Phragmen's method Expanding approvals rule Method of equal shares Fractional social choice Direct representation Interactive representation Liquid democracy Fractional approval voting Maximal lottery Random ballot Semi-proportional representation Cumulative SNTV Limited voting
Mixed systems By results of combination Mixed-member majoritarian Mixed-member proportional By mechanism of combination Non-compensatory Parallel (superposition) Coexistence Conditional Fusion (majority bonus) Compensatory Seat linkage system UK: 'AMS' NZ: 'MMP' Vote linkage system Negative vote transfer Mixed ballot Supermixed systems Dual-member proportional Rural–urban proportional Majority jackpot By ballot type Single vote Double simultaneous vote Dual-vote
Paradoxes and pathologies Spoiler effects Spoiler effect Cloning paradox Frustrated majorities paradox Center squeeze Pathological response Perverse response Best-is-worst paradox No-show paradox Multiple districts paradox Strategic voting Lesser evil voting Exaggeration Truncation Turkey-raising Paradoxes of majority rule Tyranny of the majority Discursive dilemma Conflicting majorities paradox
Social and collective choice Impossibility theorems Arrow's theorem Majority impossibility Moulin's impossibility theorem McKelvey–Schofield chaos theorem Gibbard's theorem Positive results Median voter theorem Condorcet's jury theorem May's theorem Condorcet dominance theorems Harsanyi's utilitarian theorem VCG mechanism Quadratic voting
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Primary elections or primaries are elections held to determine which candidates will run in an upcoming general election. In a partisan primary, a political party selects a candidate. Depending on the state and/or party, there may be an "open primary", in which all voters are eligible to participate, or a "closed primary", in which only members of a political party can vote. Less common are nonpartisan primaries in which all candidates run regardless of party.

The origins of primary elections can be traced to the progressive movement in the United States, which aimed to take the power of candidate nomination from party leaders to the people.^[1] However, political parties control the method of nomination of candidates for office in the name of the party. Other methods of selecting candidates include caucuses, internal selection by a party body such as a convention or party congress, direct nomination by the party leader, and nomination meetings.

A similar procedure for selecting individual candidates under party-list proportional representation can be found in open list systems; in such systems, the party primary is combined with the general election. Parties in countries using the parliamentary system may also hold leadership elections. A party's leader will typically become the head of government should that party win a majority of seats in the legislature, meaning leadership elections often select a party's de facto candidate for prime minister, much like a presidential primary.

Countries that use first-past-the-post for both the primary and general elections are often described as using a partisan two-round system to highlight the similarity to two-round (runoff) systems, particularly in two-party systems.^{[citation needed]} These similarities have led to the first round of a two-round system sometimes being called a "nonpartisan primary" in the United States.