Polls tend to vary widely in their numbers depending on how they are conducted.
RealClear Politics does helpful averages of major polls together. The editorial material surrounding it has a decidely conservative slant.
Pew Research Center for the People & the Press "The Center is an independent opinion research group that studies attitudes toward the press, politics and public policy issues. We are best known for regular national surveys that measure public attentiveness to major news stories, and for our polling that charts trends in values and fundamental political and social attitudes."
Quinnipiac University Poll Frequently cited source of political polling data
OnTheIssues.org "Every Political Leader on Every Issue"