Explanation:
United States electoral politics has been dominated by two major political parties since shortly after the founding of the republic. Since the 1850s, they have been the Democratic Party and the Republican Party. Since the last major party realignment in the mid-20th century, the Democratic Party has been the center-left or liberal party, and the Republican Party has been the center-right or conservative party (however, since 2009 with the beginning of the Tea Party movement, and the rise of Barack Obama during the 2008 United States presidential election, both the Republican and Democratic parties have shifted further from center).[citation needed] This two-party system is based on laws, party rules and custom, not specifically outlined in the US Constitution. Several third parties also operate in the U.S., and from time to time elect someone to local office.[1] The largest third party since the 1980s has been the Libertarian Party. Besides the Constitution, Green, and Libertarian parties, there are many other political parties that receive only minimal support and only appear on the ballot in one or a few states.The need to win popular support in a republic led to the American invention of voter-based political parties in the 1790s.[2] Americans were especially innovative in devising new campaign techniques that linked public opinion with public policy through the party.[3] Political scientists and historians have divided the development of America's two-party system into five eras.[4] The first two-party system consisted of the Federalist Party, which supported the ratification of the Constitution, and the Democratic-Republican Party or the Anti-Administration party (Anti-Federalists), which opposed the powerful central government that the Constitution established when it took effect in 1789.[5] Party realignments have recurred periodically in response to social and cultural movements and economic development. The modern two-party system consists of the "Democratic" Party and the "Republican" Party. However these names, while they have been in existence since before the Civil War, have not always represented the same ideology or electorate. These two parties have won every United States presidential election since 1852 and have controlled the United States Congress since at least 1856.
