http://en.wikipedia.org/wiki/Political_ideologies_in_the_United_States

"..... Political ideologies in the United States vary considerably. Persons in the U.S. generally classify themselves either as adhering to American liberalism, American conservatism or as moderates. American liberalism aims at the preservation and extension of human, social and civil rights as well as the government guaranteed provision of positive rights. It combines social progressivism and to some extent, ordoliberalism and is highly similar to European social liberalism of parties like the British Liberal Democrats, Dutch Democrats 66 and Belgian Flemish Liberals and Democrats. American conservatism commonly refers to a combination of economic liberalism and social conservatism and to an extent, libertarianism. It aims at protecting traditional values (especially on social issues) while promoting the concept of small government. The ideological position a person or party takes may be described in terms of social and economic policy. The ideological positions a person assumes on social and economic policy issues may differ in their position on the political spectrum. Milton Friedman, for example, was left-of-center on social issues but right-of-center on fiscal matters.[1] Several ideological demographics may be identified in addition to or as subgroups of liberals and conservatives with nearly every possible ideology being found in the general population. The U.S. has a de facto two-party system. The Democratic Party generally represents liberal ideals, while the Republican Party commonly represents conservative ideals. Smaller parties such as the Libertarian Party and the Greens play a minor role in American politics and are not deemed able to capture the presidency.[2]

The size of ideological groups varies slightly depending on the poll. According to a 2007 poll, 35% of Americans identified as moderate, 36% as "conservative" and 25% as "liberal."[3] In a 2005 study, the Pew Research Center identified nine typological groups. Three groups were identified as part of each, "the left," "the middle," and "the right." In this categorization system, "the right" roughly represents the Republican base, those on the "the left" the Democratic base and those in "the middle" independents. Within the left are the largely secular and anti-war "Liberals", the socially conservative but economically left"Conservative Democrats", and the economically "Disadvantaged Democrats" who favor an extended welfare state. In "the middle" are the optimistic and upwardly mobile "Upbeats", the discouraged and mistrusting "Disaffecteds," and the disenfranchised "Bystanders." The right compromises the highly pro-business "Enterprisers," the highly religious "Social Conservatives" (also known as the Christian right), and the "Pro-Government Conservatives" who are largely conservative on social issues but support government intervention to better their economic disposition.[4]...."