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CATO Institute – libertarian public policy research organization (CATO refers to itself as being “market-liberal”), supporters of small government on both economic and social issues.

Heritage Foundation – a traditional conservative policy organization, along the lines of what one might call the mainstream Republican Party.

American Civil Liberties Union (ACLU) – civil libertarians, generally not taking stands on economic issues. The ACLU’s advocacy of civil liberties takes place through both the legislature and the courts and they base their defense of those ideas on the Bill of Rights.

Brookings Institution – self-identified as nonpartisan, the Brookings Institute specializes in economics, foreign policy, issues of governance, and metropolitan policy (cities).