I cannot directly answer your question, but I think that I can indirectly address you. You have to remember, at the time, there was no question that the 5th Cir. had to be reorganized. It was by far, by number of judges, the largest circuit--imagine 25 judge en banc sessions and all of the challenges that would entail. Your question implies that the state politicians of Alabama and Mississippi would be opposed to being placed in different circuits--please correct me if I am wrong. I cannot answer that question directly, but what I can tell you is that the opposition to the reorganization came primarily from civil rights organizations. What you have to remember is that the 5th Cir. had been a great friend to the Civil Rights movement--for a representative case, look up US v. Jefferson Board of Education, the case that put the timetable on school desegregation. The 5th. Cir. definitely did not represent the will of the people residing in the circuit. So Civil rights groups, such as the NAACP and ACLU were happy with what they had and worried about what they would get.

Ultimately, inevitability was against them. The court was just too big. So while I cannot say if Alabama and Mississippi were against being placed in different circuits, I can say the primary opposition to the reorganization came from civil rights organizations.