Although an exceptional case, I would consider Menendez in NJ vulnerable too, since he is dealing with major scandals and indictment. That is probably the best case GOP pickup in a solid blue state.
Has Bernie Sanders decided if he is running again? If so, that is a super-safe seat since he is incredibly popular in Vermont. But if not, the populist agenda and anti-establishment tone could actually flip that state...
NJ is a sprawl of urban. Menendez has an interest in development of urban areas.
bernie loves to be abused and the dem party isn’t finished beating on him yet.