Final answer:
President Johnson decided not to run for president due to the unpopularity of the Vietnam War, division within the Democratic Party, and his own health problems and damaged reputation.
Step-by-step explanation:
President Johnson declared that he would not run for president due to several factors. One major reason was the growing unpopularity of the Vietnam War, which had caused division within the Democratic Party. Minnesota senator Eugene McCarthy's success in the New Hampshire primary and Robert Kennedy's announcement of his candidacy also contributed to Johnson's decision. President Johnson declared that he would not run for president due to several factors. One major reason was the growing unpopularity of the Vietnam War, which had caused division within the Democratic Party. Additionally, Johnson's health problems and damaged public standing further influenced his choice not to seek reelection.