Johnson went from his victory in the 1964 election to launch the Great Society program at home, signing the Voting Rights Act of 1965 and starting the War on Poverty. He also escalated the Vietnam War, which significantly reduced his popularity. As he had served less than 24 months of Kennedy's term, he was constitutionally permitted to run for a second full term in the 1968 presidential election under 22nd Amendment. Initially, Eugene McCarthy of Minnesota challenged Johnson as an anti-war candidate, but soon after, Senator Robert F. Kennedy too challenged him. Johnson's internal polling showed his trailing to Kennedy. On March 31, 1968, 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." While campaigning, Kennedy was assassinated shortly after midnight at the Ambassador Hotel in Los Angeles. After Kennedy's assassination, the Democratic party nominated Vice president Hubert Humphrey as their presidential candidate. Humphrey later lost the election to former vice president Richard Nixon.