He probably did not choose to run because of his health. He died in 1933 and did not feel well while he was President. Also he had already served more than one full term and no doubt believed that he had done his duty.
He wasn't interested. He said that there was no room for advancement in the United States.
Calvin Coolidge served from 1923-1929 he did not seek reelection in the 1928 election
He formally announced that he would not seek reelection to the presidency.
Johnson
the Vietnam War hurt his image
The Vietnam War hurt his image.
the Vietnam war hurt his image
that he would not seek reelection.
He declared that he would not run for an additional term as president.
It hurt his chance for reelection.
I don't think he was opposed to the idea but did not campaign for the job. He allowed his name to be placed in nomination for president at the convention in 1920 and later accepted the nomination as vice-presidential candidate. After he surprisingly became president, he agreed to run for another term. However, he did refuse to seek a third term.
The Tet offensive. Eugene McCarthy's strong showing in the New Hampshire primary
Democrat, Lyndon Johnson did not seek reelection, and therefore the democrats did not have the incumbent advantage in the race.