The US Government Accountability Office (GAO) is the “investigative arm of Congress charged with the auditing and evaluation of government programs and activities.” The GAO website features a main page on elections, as well as the following reports:

June 2010: DoD Can Strengthen Evaluation of its Absentee Voting Assistance Program (GAO-10-476)

June 2007: Action Plans Needed to Fully Address Challenges in Electronic Absentee Voting Initiatives for Military and Overseas Citizens (GAO-07-774)

September 2006: DOD Expands Voting Assistance to Military Absentee Voters, but Challenges Remain (GAO-06-1134T)

April 2006: Absentee Voting Assistance to Military and Overseas Citizens Increased for the 2004 General Election, but Challenges Remain (GAO-06-521)