The U. S. Government Accountability Office
The U.S. Government Accountability Office (GAO) is known as "the investigative arm of Congress" and "the congressional watchdog." GAO supports the Congress in meeting its constitutional responsibilities and helps improve the performance and accountability of the federal government for the benefit of the American people.
The Library of Congress, Congressional Research Service
The Congressional Research Service (CRS) works exclusively for the United States Congress, providing policy and legal analysis to committees and Members of both the House and Senate, regardless of party affiliation.