What Bill de Blasio would do to counter rise of white supremacy and deadly violence

Summary: After mass shootings in El Paso and Dayton, we examine the threat of domestic terrorism and the nation's gun policy debate. New York Mayor Bill de Blasio, one of the 2020 Democratic presidential candidates, joins Judy Woodruff to discuss the El Paso and Dayton tragedies, the "horrible reality" of the white supremacist movement and why he thinks strict gun laws have decreased homicides in New York.