(Eric Gay | The Associated Press) From left, Democratic presidential candidates Sen. Amy Klobuchar, D-Minn.; Sen. Cory Booker, D-N.J.; South Bend Mayor Pete Buttigieg; Sen. Bernie Sanders, I-Vt.; former Vice President Joe Biden; Sen. Elizabeth Warren, D-Mass.; Sen. Kamala Harris, D-Calif.; entrepreneur Andrew Yang; former Texas Rep. Beto O'Rourke; and former Housing Secretary Julian Castro are introduced for the Democratic presidential primary debate hosted by ABC on the campus of Texas Southern University Thursday, Sept. 12, 2019, in Houston.