NEW: Rep. Adam Smith on whether President Trump has the authority to declare a national emergency and have the military build the wall: "The short answer is yes," but Trump would be "wide open to a court challenge, saying where is the emergency" https://t.co/GlcWTIu29g pic.twitter.com/BwADrtQpDW— ABC News Politics (@ABCPolitics) January 6, 2019