It was first presented in Paderewski Memorial, given to US President Woodrow Wilson on 11 January 1917.
Paderewski's idea postulated rebuilding a Polish state as federation, in which constitution and law would guarantee equality to citizens, ethnic and religious groups.
On its head would be a President with a title of the King of Poland, Lithuania, Polesia and Halych.
[1] United States of Poland were to be a number of autonomous states including: Later the concept of Galicia-Podolia was supplanted by Kingdom of Halych, in separate memorial there was also postulate of incorporating an Eastern Prussia into it.
Paderewski did not pursue the matter due to large percentage of Ukrainian population living in those regions with a different politics and demography.