Kennedy 's successor Lyndon B. Johnson was able to persuade the largely conservative Congress to pass the Civil Rights Act of 1964 and with a more progressive Congress in 1965 passed much of the Great Society , which consisted of an array of social programs designed to help the poor . Kennedy and Johnson 's advocacy of civil rights further solidified black support for the Democrats , but had the effect of alienating Southern whites who would eventually gravitate towards the Republican party , particularly after the election of Ronald Reagan to the presidency in 1980 . The United States ' involvement in the Vietnam War in the 1960s was another divisive issue that further fractured the fault lines of the Democrats ' coalition . After the Gulf of Tonkin Resolution in 1964 , President Johnson committed a large contingency of combat troops to Vietnam , but the escalation failed to drive the Viet Cong from South Vietnam , resulting in an increasing quagmire , which by 1968 had become the subject of widespread anti-war protests in the United States and elsewhere . With increasing casualties and nightly news reports bringing home troubling images from Vietnam , the costly military engagement became increasingly unpopular , alienating many of the kinds of young voters that the Democrats had attracted the early 1960s . The protests that year along with assassinations of Martin Luther King Jr. and Democratic presidential candidate Senator Robert F. Kennedy ( younger brother of John F. Kennedy ) climaxed in turbulence at the hotly contested Democratic National Convention that summer in Chicago ( which amongst the ensuing turmoil inside and outside of the convention hall nominated Vice President Hubert Humphrey ) in a series of events that proved to mark a significant turning point in the decline of the Democratic party 's broad coalition
Democratic National Convention
1968 Democratic National Convention
Democratic Party (United States)