Dean was sworn in to the United States Senate on May 9, 2011. Prior to his service in the Senate, Dean was the representative for Nevada's Second Congressional District and served as Nevada's secretary of state and in the Nevada State Assembly representing Carson City.
During his time in the Senate, Dean served on the Finance Committee, Banking Committee, Veterans' Affairs Committee, and Commerce Committee. While in the U.S. House of Representatives, he served on Ways and Means Committee.
Dean was rated as the fifth most bipartisan senator by the Lugar Center and Georgetown University McCourt School of Public Policy. This bipartisanship enabled him to pass over 100 different pieces of legislation.