In politics, a partisan is a committed member of a political party.
A political party is a group of people who come together to contest elections and hold power in the government.
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In multi-party systems, the term is used for politicians who strongly support their party's policies and are reluctant to compromise with their political opponents.
A multi-party system is a system in which multiple political parties across the political spectrum run for national election, and all have the capacity to gain control of government offices, separately or in coalition.
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Before the American National Election Study began in 1952, an individual's partisan tendencies were typically determined from their voting behavior.
Since then, "partisan" has come to refer to an individual with a psychological identification with one or the other of the major parties.