Actually Sessions Yugest mistake was to hire Rosenweasel as his assistant.
Sessions is surrendering all decision-making authority on everything of importance to Rosenstein and other operatives of the Deep State and has done that since he took office. What a miserable, cowardly, little man he is at a time when we need (figurative) a GIANT of a man in that office.
I don’t think it was a mistake...It was intensional.