FiveThirtyEight Senate forecast update for Oct. 19, 2018 Video

  • Now Playing: Sen. Sanders: Democrats ‘have to end one party rule’ by winning in midterms


  • Now Playing: Donna Brazile on Democrats in midterms: ‘Energy, good-quality candidates and… money’




  • Now Playing: President Trump riles up his base by targeting immigrants entering illegally




  • Now Playing: Republican strategist: ‘Trump is on every ballot’ in the midterm elections




  • Now Playing: Matt Gutman: Caravan is a ‘mass of humanity’ heading toward U.S. border




  • Now Playing: 538’s Nate Silver: ‘It’s hard to find a clear path for Democrats’ to win Senate




  • Now Playing: Credibility of Saudi explanation for Khashoggi’s killing questioned by US, Europe




  • Now Playing: Trump takes shots at Joe Biden during Nevada rally




  • Now Playing: On the trail: Does Beto O’Rourke have a chance against Ted Cruz in Texas?




  • Now Playing: Schiff: Khashoggi killing should be ‘relationship-altering event for’ US and Saudis




  • Now Playing: Khashoggi’s WaPo editor: ‘Human life should not have a price tag on it’




  • Now Playing: ABC News’ Paula Faris interviews Texas Senate candidate Beto O’Rourke




  • Now Playing: ABC News’ Paula Faris interviews Texas Senate candidate Ted Cruz




  • Now Playing: Thousands of migrants attempt to escape violence in Central America




  • Now Playing: Trump blames Democrats for migrant caravan




  • Now Playing: Russian woman arrested in alleged plot to meddle with midterms




  • Now Playing: Police clash with migrant caravan near border




  • Now Playing: Caravan of migrants tears down fence on Mexico-Guatemala border




  • Now Playing: The Briefing Room: Migrant caravan reaches Guatemala-Mexico border




  • Now Playing: Trump comments perceived by some as encouraging violence