In August 1921 de Valera had DÃ il Ã ireann change the 1919 DÃ il Constitution to upgrade his title from prime minister to President of the Republic . In August 1921 , de Valera secured DÃ il Ã ireann approval to change the 1919 DÃ il Constitution to upgrade his office from prime minister or chairman of the cabinet to a full President of the Republic .