See Elections tab on the Government home for more information sources related to U.S. elections.
Politican ratings - Project Vote Smart reports on performance evaluations from all special interest groups who provide them, regardless of issue or bias.
The Congressional Research Service (CRS), a division of the Library of Congress, produces analytical, non-partisan reports on topics of interest to members of Congress. In 2018, Congress passed a law directing the creation of a public access site to the reports, ending the legal requirement prohibiting CRS from providing its products to the public.
Prior to the creation of the above CRS site from LoC, there were a few archival options for locating some of the CRS reports, such as:
UNT CRS Archive - Search or browse by country, decade, or topic the University of North Texas Digital Library archive of CRS reports.
Some topical collections:
Author, A. A. (Year). Title of report in sentence case and italics (CRS Report No. xxxxxxx). Retrieved from Congressional Research Service website: URL
Example:
Erwin, M. C. (2011). Intelligence issues for Congress (CRS Report No. RL33539). Retrieved from Congressional Research Service website: http://www.fas.org/sgp/crs/intel/RL33539.pdf