What factors explain the growing tensions between SNCC and SCLC and the increasing criticisms of King by SNCC workers?

The Southern Leadership Christian Conference (SCLC) was founded in 1957 by Reverend Martin Luther King, Jr. The Student Nonviolent Coordinating Committee (SNCC, pronounced "snick") was set up in 1960. Both played important roles in the turbulent sixties—especially in the South—as Black people fought for equality.
James Forman (1928–2005) was the executive secretary of SNCC. He explained that SNCC leadership was indigenous, or based in the community. The plan was to have a broad-based movement that would endure. Forman believed that the SCLC was too dependent on the charismatic King for leadership and fundraising. These differences in leadership led to differences in style and methods as both groups fought for civil rights.
SNCC was impatient with King's seemingly cautious leadership style and was more militant. It was less will to compromise than King was. SNCC was a grassroots organization which did voter registration drives; in one such drive, three SNCC workers were murdered. By 1966, Stokely Carmichael had taken over SNCC, and he abandoned King's nonviolent approach to protesting. Black power replaced peaceful protest as the vehicle for change. Carmichael soon left SNCC and joined the more radical Black Panthers. H. Rap Brown, Carmichael's successor as head of SNCC, also joined the Black Panthers. Within a few short years, SNCC ceased to exist.
After King's assassination in 1968, the SCLC declined. His successors lacked his charisma and influence. There were divisions in the ranks, too. The SCLC still exists today, but it lacks the power it once enjoyed.