Hitler came into power roughly at the same time FDR was elected to end the depression that turned into the "Great Depression". According to a book "In the garden of the beasts" by Eric Larson, FDR knew about the atrocities that were happening in Germany under Hitler and he did nothing except pester his Ambassador to try to recover money that was owed to the Allies as a result of Germany's WW1 surrender. The U.S. had no central intelligence agency prior to WW2 so the FDR administration was forced to rely on accounts from the Ambassador to Germany for a consideration of the political climate in Europe after WW1 but for some reason the FDR administration didn't care about graphic accounts of Jews and even Americans brutalized on the streets of Berlin.