Why do you believe that's even a possibility? He's had a 15-20 lead in every poll, his opponent is the same dude who lost to Carper by +30 points and has fundraised literally dozens of thousands of dollars (like two dozens) , nobody is airing tv ads... perhaps Coons won't win by 20, but I see no way this even comes close to competitive absent some major scandal. Definitively safe D.
Kevin Wade is obviously an experienced candidate and Coons is less known and less liked than Carper. Also, Coons is running in the worst Democratic year since the dawn of time, and so no seat is safe in muh Republican wave.
