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.