Heuss became a member of the German Democratic Party ( Deutsche Demokratische Partei , DDP ) and was a member of parliament for two periods . Heuss became a member of the German Democratic Party ( Deutsche Demokratische Partei , DDP ) , the political heir of the Fortschrittliche Volkspartei , in 1918 and was a member of parliament in the Reichstag from 1924 to 1928 and from 1930 to 1933 .