Rahm Emanuel on mayors and the 2020 Democratic primary

Rahm Emanuel has served as a top adviser to Presidents Clinton and Obama, a three-term congressman from Illinois and a two-term mayor of Chicago. But in his new book, “The Nation City,” the longtime Democrat argues that mayors are today’s most effective U.S. government officials. Emanuel sits down with Judy Woodruff to discuss that idea as well as his fears about "reckless" progressives in 2020.