Hoopes was born in LaVale, Maryland, and educated at the George School and the University of Wisconsin School of Agriculture. He ran for multiple offices with the Socialist nomination and served in multiple position within the Socialist Party; with him later becoming chairman of the party. He served as the Socialist Party's vice-presidential nominee during the 1944 presidential election and as the party's presidential nominee during the 1952 and 1956 presidential elections. Hoopes conducted the last presidential campaigns of the Socialist Party of America. He briefly joined the Social Democratic Federation in the 1930s before returning to the Socialist Party and later joined the Socialist Party USA after the dissolution of the Socialist Party.