He brought recognition to Guam's unique people by lifting the ban on betel nut (pugua) importation into the US Customs Zone, inclusion in the National World War II Memorial, the creation of Chamorro Standard Time (CST) and participation in national commemorative events. As a member of the Hispanic and Asian Pacific American Caucuses, he spoke out for the protection of immigrant rights, educational opportunities and sensitivity to language issues. As chairman of the Congressional Asian Pacific American Caucus in the 106th Congress, he led the effort to include Asian Pacific Americans in scholarship programs, was instrumental in the development of the White House Initiative on Asian Americans and Pacific Islanders, spoke out against racial profiling and for including Pacific Islanders as a demographic category in federal programs. Underwood declared his candidacy for the 2002 gubernatorial election and was a candidate in the November 2002 General election. His running mate for Lt. Governor was Senator Thomas "Tom" Ada. Underwood was defeated by Felix Perez Camacho in the general election on November 3, 2002. Underwood ran again as a Democrat for Governor of Guam in 2006, with running mate Frank Aguon for Lieutenant Governor. The Underwood-Aguon team faced former governor Carl Gutierrez and Senator Benjamin Cruz. He defeated his main Democratic rival, for the Gutierrez-Cruz team in the primary election on September 2, 2006. But on November 7, 2006 he was defeated during the general elections when he re-elected to incumbent Republican Governor Felix Perez Camacho, along with his new running mate Lt. Governor-elect Dr. Michael Cruz for the percentage voters from 50%-48%. In 2008, Underwood was selected to begin a 5-year term as the tenth president of the University of Guam and has continued to hold this position as of 2016. In June 2018, Underwood retired as President of the University of Guam and was succeeded by Thomas W. Krise. On June 30, 2020, it was announced that Underwood is running for Guam Delegate to the U.S. House of Representatives is part of the Democratic primary election to face against Guam Congressional Delegate Michael San Nicolas.