The best explanation for the impact of post-Reconstruction political leadership on African Americans in South Carolina is: African Americans lost almost all political power through intimidation and corruption.
After Reconstruction, many factors such as voter suppression tactics, intimidation from groups like the Ku Klux Klan, and the corruption within political systems led to the significant decline of African American political influence in the South, including South Carolina. While there were brief periods of limited power and attempts at regaining influence, the overall dominant narrative is that post-Reconstruction efforts systematically disenfranchised African Americans.