Vote splitting

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Vote splitting is an electoral effect in which the distribution of votes among multiple similar candidates reduces the chance of winning for any of the similar candidates, and increases the chance of winning for a dissimilar candidate. This is commonly known as the spoiler effect, which can discourage minor party candidacies.

Vote splitting most easily occurs in plurality voting (also called first-past-the-post) in which each voter indicates a single choice and the candidate with the most votes wins, even if the winner does not have majority support.^[1] For example, if candidate A1 receives 30% of the votes, similar candidate A2 receives another 30% of the votes, and dissimilar candidate B receives the remaining 40% of the votes, plurality voting declares candidate B as the winner, even though 60% of the voters prefer either candidate A1 or A2.