Greg Sargent: Raging, isolated Trump retreats deeper into his bubble

President Donald Trump, having clearly spent the morning absorbed in the careful study of immigration issues, just unleashed this thoughtful and considered policy prescription.Trump tweeted: “We must have Security at our VERY DANGEROUS SOUTHERN BORDER, and we must have a great WALL to help protect us, and to help stop the massive inflow of drugs pouring into our country!”We must have Security at our VERY DANGEROUS SOUTHERN BORDER, and we must have a great WALL to help protect us, and