Sen. McCaskill on Clinton making history, Sanders' role in race
Sen. Claire McCaskill was one of the first members of Congress to endorse Hillary Clinton for president, nearly two years before Clinton started her 2016 campaign. Now as Clinton makes history as the first woman to become the presumptive nominee of a major U.S. political party, McCaskill joins "CBS This Morning" to discuss what this means to her personally and the state of the 2016 race.