With the U.S. population turning against the war, LBJ knew he stood little chance of reelection. Even though he had won by a huge landslide in 1964 and had passed the most legislation, he hardly beat an obscure challenger from his own party in an early primary.
What was worse, he was finally opposed by Robert Kennedy, the younger brother of the now-revered President Kennedy. In a surprise announcement, LBJ declared he wouldn't run again. Vietnam had ruined him. Robert Kennedy swept the primaries but was assassinated by an Arab immigrant only a month after Martin Luther King died. (As with the JFK assassination, no real evidence of a conspiracy in the second Kennedy killing has ever come to light.)
In the midst of demonstrations and police violence a few weeks later, the Democrats nominated Johnson's loyal vice president Hubert Humphrey. With a Southern segregationist running as a third-party candidate, Humphrey narrowly lost the presidential election to Republican former vice president Richard Nixon, who was elected on the promise that he was the experienced one who could bring an honorable peace both to Vietnam and to the demonstration-thronged streets of America.
The established order versus the counterculture
The U.S. was deeply divided between the established order and a counterculture of mostly younger people who opposed the war and supported a civil rights revolution to liberate women, blacks, and other minorities. A social goal of the movement was to expand free personal behavior and expression. The counterculture also included a small violent fringe of Black Panthers, who advocated armed defense of African American interests, and mostly white radical Weathermen, who were willing to be violent because they thought the times demanded force. The Weathermen took their name from the words of a Bob Dylan song: "You don't need a weatherman to tell which way the wind blows . . ." Most of the counterculture, however, was a large peaceful tribe of flower-wearing and mind-expanding hippies.
The U.S. actually has an unbroken and under-reported tradition of small group opposition to established power that limits any of the rights outlined in the Declaration of Independence. During the 1960s and '70s, the opposition got bigger; a lot of changes that had been in the works for hundreds of years came to the forefront. After much conflict, the social revolutionaries settled down to work for a new order that was freer than the old.
During the height of the demonstrations, Richard Nixon's vice president, Spiro Agnew, called the youthful protestors "nattering nabobs of negativism." Several of the young people cut off their easily identified long hair and sent it to Agnew in a pillow, neatly embroidered with the words "Now we could be anywhere."