The fact is, that the Jews have never voted republican, and that did not start in 1920, in fact, in 1920, the Jews didn’t only vote against the republicans, they voted 38% for the socialist party.
While you were pretty vague in your post, and mostly trying to dispute history with implying, I can find the 1880s Jewish socialism push, and their involvement in promoting the left in their big city politics, but I can’t find the time when the Jews were voting majority republican.
Really, you can find an 1880s Jewish socialism push (in the US)? Eastern European Jews didn't arrive in the US in significant numbers until the first major pogrom in Russia in 1880. Earlier German Jews in the US were not particularly big on socialism. They were too busy racking up fortunes by being capitalists.