What new Iowa poll numbers mean for 2020 Democrats

Iowa plays an outsized role in presidential politics, and new poll numbers from that state could influence how different Democratic candidates' focus their campaigns. The poll by The Des Moines Register and CNN puts Sen. Elizabeth Warren two points ahead of former Vice President Joe Biden, with Sen. Bernie Sanders in third. Judy Woodruff breaks down the numbers with J. Ann Selzer of Selzer & Co.