 That was Senator Abraham Ribicoff at the chaotic 1968 Democratic National Convention in Chicago, something Democrats do not want to see repeated next month when they are back in the Windy City. Speculation that President Biden could drop out of the race has many wondering how his replacement would be chosen and how a possible contested or open convention might work. We've got an expert, distinguished professor of history at American University, Ellen Lichtman. Professor, welcome to the show.