As LBJ was known to be a blatant racist, did he truly believe in the civil rights cause, or were his efforts to pass civil rights legislation largely a part of party politics and public image with the African American population?
I don't know if "blatant racist" is the right description of LBJ. Robert Caro makes a compelling argument in his multi-volume bio The Years of Lyndon Johnson that Johnson did support the cause of civil rights privately, regardless of the racist language he often used in his daily life. His early life in Texas gave him an insight into the struggles of the Hispanic minority there, and to the hardships of poor people generally. As to LBJ's views on the party politics of civil rights, it is possible to do the right thing and benefit from it politically. If you're interested In Johnson, I can't recommend Caro's books enough. They're brilliant.