LBJ & Hoover didn’t like each other. Johnson tried to have Hoover eased out as FBI director and when he realized it was going to be too difficult, LBJ muttered, “well, it’s probably better to have him inside the tent p***ing out, than outside p***ing in”.
Hoover eventually got control over LBJ over the civil rights and anti-war movements. LBJ was convinced the commies were behind both, and had Hoover spy on them. Of course that was how Hoover worked. Once he got someone in bed with him engaging in some illegal act, he had them.
The only one who really held this off was Nixon. He set up his own group to do such things so he would not be in debt to Hoover (the ‘Plumbers” as they were called.) It really PO’d Hoover, and most people feel it was him that ratted out the Plumbers at the Watergate Hotel.