LBJ wanted to show up at the 1968 Democratic Convention and ask for the nomination.

Newly declassified tapes reveal. This plan arose during the convention, while the big "whole world is watching" protests raged.

[LBJ] planned to leave Texas and fly into Chicago. He would then enter the convention and announce he was putting his name forward as a candidate for a second term....

[Chicago Mayor Richard] Daley assured him enough delegates would support his nomination but the plan was shelved after the Secret Service warned the president they could not guarantee his safety.

Also at that link, LBJ "orders the Nixon campaign to be placed under FBI surveillance and demands to know if Nixon is personally involved" in some dealings involving Vietnam peace talks.