Public Opinion
Gallup Poll
The Roper Center
Pew Poll
Zogby International
Real Clear Politics
Polling Report
Marist Institute Polls
The Polling Company
Mason-Dixon Polling & Research
Harris Interactive (Wirthlin Worldwide/Harris Polls)
American Presidency Project (Popularity Over Time)
Survey Research Resources (Abelson)
Inter-University Consortium for Political and Social Research (ICPSR) – General Social Survey (GSS)