Lyndon B. Johnson
1968 presidential election

As he had served less than two years of President Kennedy's term, Johnson was constitutionally eligible for election to a second full term in the 1968 presidential election. Despite Johnson's growing unpopularity, conventional wisdom held that it would be impossible to deny re-nomination to a sitting president. Johnson won a narrow victory in the New Hampshire presidential primary on March 12, against Senator Eugene McCarthy 49–42%, but this close second-place result dramatically boosted McCarthy's standing in the race. Senator Robert F. Kennedy announced his candidacy on March 16. At the end of a March 31 speech, Johnson shocked the nation when he announced he would not run for re-election by concluding with the line: "I shall not seek, and I will not accept, the nomination of my party for another term as your president". The next day, his approval ratings increased from 36 percent to 49 percent.

Historians have debated the factors that led to Johnson's surprise decision. Shesol says Johnson wanted out of the White House but also wanted vindication; when the indicators turned negative he decided to leave. Woods writes that Johnson realized he needed to leave in order for the nation to heal. Dallek says that Johnson had no further domestic goals, and realized that his personality had eroded his popularity. His health was not good, and he was preoccupied with the Kennedy campaign; his wife was pressing for his retirement and his base of support continued to shrink. Leaving the race would allow him to pose as a peacemaker. Bennett, however, says Johnson "had been forced out of a reelection race in 1968 by outrage over his policy in Southeast Asia." Johnson may also have hoped that the convention would ultimately choose to draft him back into the race.

Vice President Hubert Humphrey entered the race after Johnson's withdrawal, making the 1968 Democratic primaries a three-way contest between Humphrey, Kennedy, and McCarthy. Kennedy cut into McCarthy's liberal and anti-war base, while also winning the support of the poor and working class. He won a series of primary victories, but was assassinated in June by Sirhan Sirhan, an Arab nationalist. With Johnson's support, Humphrey won the presidential nomination at the tumultuous 1968 Democratic National Convention, held in Chicago in late August. Violent police attacks against anti-war protesters in Chicago marred the convention.

Humphrey's polling numbers improved after a September 30 speech in which he broke with Johnson's war policy, calling for an end to the bombing of North Vietnam. In what was termed the October surprise, Johnson announced to the nation on October 31, 1968, that he had ordered a complete cessation of "all air, naval and artillery bombardment of North Vietnam", effective November 1, should the North Vietnamese government be willing to negotiate and citing progress with the Paris peace talks.

Republican nominee Richard Nixon won the election.
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