They are Executive agencies under the charge of the Executive and Trump can fire any and all at will
He will not get any new ones confirmed in the senate...remember what Turdle Mconnel said. Also, the next in line are deep state too. He would have to fire at minimum 3-4 levels of management from EACH department. How long do you think it would take CONgress to impeach and remove Trump from office for firing a minimum of 6 top heads of the FBI, DOJ, CIA, and throw in the IG, a Obama appointee that let Holder slide for his Felony. Trump is screwed, with no way out. and so are we. Time will tell, and it has been giving us a example of what is to come of these criminals....nothing.