When the former secretary of state and C.I.A. director Mike Pompeo, a man who had dealt firsthand with autocrats like Vladimir Putin and Xi Jinping, described Randi Weingarten as “the most dangerous person in the world” last November, it seemed as though he couldn’t possibly be serious. Weingarten is 65 and just over five feet tall. She is Jewish and openly gay — she’s married to a rabbi — and lives in Upper Manhattan. She is the longtime president of the American Federation of Teachers, which is not even the country’s biggest union of public school educators. The A.F.T. did give in excess of $26 million to Democratic candidates and causes in the 2022 election cycle, but the Carpenters and Joiners union gave more than twice as much. The public education system may not be very popular right now, but both Democrats and Republicans tend to like their local schools and their children’s teachers. The unions that represent those teachers, however, are more polarizing. One reason for th...