Purple is a common term in politics for governments or other political entities consisting of parties that have red and blue as their political colours. It is of particular note in two areas: in the politics of the Netherlands and Belgium and in the politics of the United States.
Belgium and the Netherlands
"Purple" (Dutch: Paars) is the nickname of a government coalition of social democrats and liberals together, excluding Christian democrats. It is derived from the combination of the colour of the social democrats (red) and liberals (blue).
Both the Netherlands and Belgium have had such governments. In the Netherlands the two cabinets of Prime Minister Wim Kok (Kok I and Kok II, 1994–2002) were composed of social democrats (the Labour Party, PvdA), conservative liberals (People's Party for Freedom and Democracy, VVD) and progressive liberals (Democrats 66).
In the 2010 Dutch cabinet formation the possibilities for a Purple-plus cabinet (the original "purple" coalition of PvdA, VVD, D66 plus GreenLeft) was investigated. Since 5 November 2012, following the 2012 Dutch general election, the VVD has been the senior partner in the second Rutte cabinet, a grand coalition Purple government with the PvdA.
In October 2013 the Second Rutte cabinet (VVD and PvdA), which has no majority in the Senate, reached a budgetary agreement with D66 and the smaller Christian parties ChristianUnion and the Reformed Political Party (SGP). This occasional coalition is nicknamed "purple plus the Bible" (Paars met de Bijbel) as it includes the purple parties VVD, PvdA and D66 plus the Bible-minded parties ChristianUnion and SGP. The term "purple plus the Bible" had already been used in February that year, when the same parties reached an agreement on modernising the housing market.
In Belgian politics, the term is used as a term for the two federal governments of Prime Minister Guy Verhofstadt, from 1999 to the general elections of 2007. These cabinets consisted of the Flemish and Francophone social-democratic parties (SP.A and PS) and the Flemish and Francophone liberal parties (Flemish Liberals and Democrats and the Liberal Reformist Party, which later became Open VLD and the Reformist Movement). The first government also included the Flemish and Francophone green parties Agalev and Ecolo.
In the United States, a "purple" state is one where popular support for the Republican Party (red) and Democratic Party (blue) is approximately equal; such states, in elections for the President of the United States, are termed "swing states" and are highly-targeted on account of the Electoral College system of electing the President.
Since the system of first-past-the-post voting generally ensures that either one party or the other has an absolute majority in a legislative chamber, coalitions between the two parties are naturally rather rare. However, a "purple" coalition between the Democrats and dissident Republicans has controlled the Alaska Senate since 2006.