Sorry you missed the historical time frame. My statement is not “totally incorrect.” That small number of Jews that you refer to that arrived in the USA following the European Revolution of the late 1840s could join none other than a conservative party. In contrast, the great number of American Jews trace thir heritage to East European arrivals in 1890-1910. By then the radical political elements influenced by European political thought were forming in America, and they soon had a leader in Eurgene Debs. The number of Jews who arrived in the USA in the WWI-WWII period don’t amount to much as the leadership of American Jewry — on the left, right and center — was by then pretty well fixed.
They were still initially radicalized in Europe, not here, as your original post suggested.