![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_4x3_384.jpg)
![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_4x3_144.jpg)
![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_4x3_384.jpg)
![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_16x9_240.jpg)
![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_4x3_608.jpg)
![](https://s.abcnews.com/images/WNT/190910_wn_debate1_642_hpMain_16x9_992.jpg)
Now Playing: Former Houston mayor talks Democratic debate and beating Trump
Now Playing: FiveThirtyEight Politics Podcast: How to win this week’s debate
Now Playing: The ABC Democratic Debate – Tomorrow at 8e|7c|5p on ABC
Now Playing: Supreme Court rules in favor of Trump immigration policy
Now Playing: What to watch for in ABC News’ Democratic debate
Now Playing: 10 Democratic candidates on debate stage for 1st time
Now Playing: SigDigs: Sept. 12, 2019
Now Playing: Joe Biden, Elizabeth Warren to debate side-by-side for 1st time
Now Playing: White House moves to ban certain e-cigarettes
Now Playing: Houston debate stage set ahead of 3rd DNC primary debate
Now Playing: Immigration attorney talks difficulties of asylum system in America
Now Playing: Spotlight on what it will take for Democrats to win in 2020
Now Playing: 6 months without a White House press briefing
Now Playing: Pete Buttigieg’s friends on what he was like when he was in high school and college
Now Playing: Trump addresses Bolton firing
Now Playing: Trump and Bolton differ on departure
Now Playing: Democratic debate: What to watch for
Now Playing: Bolton pushes back on Trump saying he was fired
Now Playing: Uninsured Americans up 2 million: Census Bureau
Now Playing: Democratic debate stage set in timelapse footage