"Johnson's escalation of the Vietnam War ruined much of his credibility as President. Johnson was wary of potential political attacks from the right for losing a portion of the world to communism. Johnson believed that if Vietnam fell to the Communists, his presidency would be considered soft on communism, at the same time undermining his grand domestic agenda. Johnson began bombing North Vietnam in 1965 and it continued for the next 7 years through the Nixon Administration. Over time, Johnson escalated the number of troops and active military involvement in Vietnam. Soldier casualties were mounting and soon chants were heard, "Hey, Hey LBJ, How many boys did you kill today?" By the end of his presidency, Johnson turned into a recluse, rarely leaving the White House.<2>"
"Entering the 1968 election campaign, initially, no prominent Democratic candidate was prepared to run against a sitting president of the Democratic party. Only Senator Eugene McCarthy of Minnesota challenged Johnson as an anti-war candidate in the New Hampshire primary, hoping to pressure the Democrats to oppose the war. On March 12, McCarthy won 42% of the primary vote to Johnson's 49%, an amazingly strong showing for such a challenger. Four days later, Sen. Robert F. Kennedy of New York entered the race. Internal polling by Johnson's campaign in Wisconsin, the next state to hold a primary election, showed the President trailing badly. Johnson did not leave the White House to campaign.
Johnson had lost control of the Democratic Party, which was splitting into four factions, each of which despised the other three. The first consisted of Johnson (and Humphrey), labor unions, and local party bosses (led by Chicago Mayor Richard J. Daley). The second group consisted of students and intellectuals who were vociferously against the war and rallied behind McCarthy. The third group were Catholics, Hispanics and African Americans, who rallied behind Robert Kennedy. The fourth group was traditional white Southerners, who rallied behind George C. Wallace and the American Independent Party. Vietnam was one of many issues that splintered the party, and Johnson could see no way to win Vietnam<50> and no way to unite the party long enough for him to win re-election.<66>
In addition, Johnson was concerned that he might not make it through another term. Therefore, at the end of a March 31 speech, he shocked the nation when he announced he would not run for re-election: "I shall not seek, nor will I accept the nomination of my party for another term as your President."<67> "
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