His aides Max Kampelman and Bill Connell began to set up an organization and held meetings with Humphrey and his advisors, encouraging him to start a campaign.
Humphrey set up offices for preparation, and unsuccessfully courted Larry O'Brien as campaign manager.
This traditional approach was criticized by the other candidates, who hoped to win the nomination from popular support.
Robert Kennedy was assassinated in June 1968, leaving Mc Carthy as his only opponent, until the 1968 Democratic National Convention, when Senator George Mc Govern of South Dakota ran as the successor of Kennedy.
The Hubert Humphrey presidential campaign of 1968 began when Vice President of the United States Hubert Humphrey of Minnesota decided to seek the Democratic Party nomination for President of the United States following the announcement by President Lyndon B.
Johnson that he would not seek the party's nomination.
During the general election, Humphrey faced former Vice President Richard Nixon of New York, the Republican Party nominee.
Nixon led in most polls throughout the campaign, and successfully criticized Humphrey's role in Vietnam, connecting him to the unpopular president and the general disorder in the nation.
Kennedy of New York, became the main opponents for Humphrey.
The Johnson campaign tried many tactics to negate the war's detractors before the New Hampshire primary, including the circulation of the slogan, "the communists in Vietnam are watching...don't vote for fuzzy thinking and surrender".
Humphrey tried to encourage Johnson to be more involved in the campaign, but the President seemed uninterested.
He delayed meetings with Indiana Governor Roger Branigin to arrange a favorite son "stand in" for the campaign, and neglected to hire the campaign's 1964 campaign manager Larry O'Brien, despite Humphrey's insistence.
But Humphrey was able to convince Johnson to speak to the influential National Farmers Union in Minneapolis, ahead of the Wisconsin Primary.