I think that one particular reason why the Chicago Campaign in 1966 fell short was because the racism Dr. King sought to counter in the North was much more insidious and challenging than that of the South.  The overt racism in the South was a force that could be easily identified.  Lynchings, the Klan, racist authority structures that did not hide their disdain and acceptance of segregation practices and violence against people of color were adversaries that could be identified without hesitation.  When Dr. King turned to the North, his enemy was institutional and economic, forces that can hide from scrutiny much easier.  Seeking to attack the embedded slum conditions was more of a challenge because it sought to bring light to economic practices and opportunity as much as racial injustice.  Dr. King, himself, conceded the difficult and elusive nature of this particular adversary:

In the South, we always had segregationists to help make issues clear.… This ghetto Negro has been invisible so long and has become visible through violence’’ (Cotton, 26–28 August 1965).

This is where Dr. King's challenges existed.  He was fighting a racial challenge as well as an economic one.  In the Southern phase of his fight, the racial element was more pronounced and easier to identify.  Now, in the North, Dr. King was depicted as battling the reality of the free market and seeking to radically change economic structures and practices, labels that diluted his overall effectiveness when compared to his efforts in the South.  At the same time, the diversity of the African- American community in Chicago helped to weaken the overall solidarity of the movement.  Individuals that believed in King's effectiveness also felt the need to confront in a direct manner those who were throwing stones, perhaps embracing a stance of self- defense that Dr. King abhorred.  In the South, the element of Christianity, seeking to make a moral and spiritual stand through the use of nonviolence, was part of the success of the movement.  Cast in Biblical terms, the oppression of Southern racism was poised against Christian fighters who embraced nonviolence as representative of Jesus' teachings in striving for social change.  In Chicago, the ground game was more secular, with activist and nationalistic stresses being evident, causing the moral stature that Dr. King sought to become a bit more muddled.  In this, Dr. King did not find the immediate success he sought and achieved so clearly in the South.