NASA Commercial Crew Program: Significant Work Remains to Begin Operational Missions to the Space Station, Report to Congressional Committees [open pdf - 2MB]
From the GAO [Government Accountability Office] Highlights: "Since retiring the Space Shuttle in 2011, NASA has depended on Russia to transport astronauts to the International Space Station (ISS). NASA's Commercial Crew Program is a multibillion dollar effort to re-establish a U.S. capability to get a crew to space, but it is years behind schedule. NASA may have to continue to rely on the Russian transport option or risk losing access to the ISS in 2020."
Government Accountability Office: http://www.gao.gov/