From 1919, Lohse was first an associate at the Schleswig-Holstein Farmers' Association, and then as of 1920 General Secretary of the Schleswig-Holsteinische Bauern- und Landarbeiterdemokratie.
Lohse, who had been a member of the Reichstag since 1932, was appointed shortly after the Nazis' seizure of power as Oberpräsident (High President) of the Province of Schleswig-Holstein.