 On May 15, 1935, he was named Minister to Romania, serving there from July 24, 1935, to September 3, 1937.He was then Minister to Switzerland from September 10, 1937, to October 14, 1947.As Ambassador to Switzerland, Harrison was sympathetic to Jewish rescue and relief operations and worked closely with Gerhardt Riegner, the representative of the World Jewish Congress in Geneva and sent several reports regarding the murder of the Jews of Europe to the United States Department of State in Washington D.C.