As a prominent business leader and former diplomat, Partridge developed "senior statesman" status that led to service on various boards and commissions, in the 1910s and 1920s, including the state public safety committee that managed Vermont's participation in World War I and the public corporation that aided in Vermont's recovery following the Great Flood of 1927. In December 1930, Governor John E. Weeks appointed Partridge to the U.S. Senate to fill the vacancy created by the death of Frank Greene. Partridge lost the Republican nomination to Warren Austin in the March 1931 primary, and in overwhelmingly Republican Vermont, Austin easily defeated Democrat Stephen M. Driscoll in the general election. Partridge retired in 1935, and resided in Proctor. He died there on March 2, 1943 and was interred at South Street Cemetery in Proctor.