Representative Alexandria Ocasio-Cortez drew a hard line at the University of Chicago last week, rejecting calls from fellow progressives to work alongside former Representative Marjorie Taylor Greene on Gaza policy."I personally do not trust someone like Marjorie Taylor Greene, a proven bigot and antisemite, on the issues of what is good for Gazans and Israelis," Ocasio-Cortez said Friday at an event hosted by the Institute of Politics. "I don't think that it benefits our movement, in that instance, to align the left with white nationalists."For years, critics have blamed purity tests—demanding ideological perfection from coalition partners—as a Democratic weakness that...