Thirty years ago things were different. Generally speaking a Jewish politician even a secular one could have been counted on to have a Jewish identity and identify with Jewish causes. Even frum ones.
Today we are better off with a conservtive non-Jew than a secular Jewish politician. And from people like Bernie Sanders and the other left wing “Jewish” politicians we can only expect hostility. Even worse than from the average non-Jewish politician.
If a politician makes reference to his being Jewish in a context other than when it benefits him politicly it’s one thing if he lights a Menorah. When a guy like Doug Emhoff lights a menorah all I can say is “What are you celebrating? Your side lost!”