Actually, it's an old one.
The real history of it is that the regime of Czar Nicholas II wrote a book titled "Protocols of the Learned Elders of Zion" to rationalize pogroms against Russian Jews. The book was translated and became a worldwide bestseller, catalyzing anti-semitic right-wing movements around the world including, ultimately, the Nazi Party. For the first half of the 20th century, Jews were basically treated as anything from an "unsavory element" to a sinister menace even in the United States. Henry Ford wrote a screed against Jews called "The International Jew." Basically, right-wingers had a very simple explanation for all their problems: Jews. Jews in government, Jews in the media, Jews in academia. Jews, Jews, Jews. If they didn't like a fact printed by a newspaper, it was because it was part of the "Jew-run media" according to conservatives. If they didn't like a study from a university, it was because of all the "Commie Jews" on the faculty. And the right didn't even stop using it after WW2 - it just eventually stopped being effective because nobody cared anymore much past the '70s. So then moved on to new bugaboos, new propaganda bogeyman, new people to inspire hate and violence against. Because that's just the sort of people conservatives are.
