 In the early 1960s, the topic of civil rights was coming to national prominence with sit-ins and marches organized by Martin Luther King Jr. and other black leaders. In 1963, President John F. Kennedy sent a comprehensive civil rights bill to Congress, based largely on the ideas that Humphrey had been placing before the Senate for the previous fifteen years. The bill passed the House in early 1964, but passage through the Senate was more difficult, due to southern segregationists who filibustered for 75 days. Finally, in June 1964, the Civil Rights Act of 1964 became law. Humphrey called this his greatest achievement. Lyndon B. Johnson recruited Humphrey for his running mate in the 1964 presidential election, and Humphrey became Vice President of the United States. Governor Karl Rolvaag (DFL) appointed Walter Mondale to fill Humphrey's Senate seat. Humphrey voiced doubts about the 1965 bombings of North Vietnam, which alienated him from Johnson. He later defended Johnson's conduct of the Vietnam War, alienating himself from liberals, who were beginning to oppose the war around 1967. In the 1968 presidential election, Humphrey ran against Richard Nixon and Independent candidate George Wallace and lost the popular vote by only 0.7 %. Humphrey later returned to the Senate in 1971 after Eugene McCarthy left office.
