You made my point that it was a political problem and not a slavery issue.
Looking to affix blame for the war, many in the press and government gave factual status to the idea that westward expansion of slavery was the primary factor leading to war. They relegated the increasing division of the two economic and political worlds as secondary factors.
The "political problem" was that the South was losing its ability to keep enough votes in the Senate to permanently preserve slavery.
The Confederate constitution specifically removed one right that the US Constitution's Bill of Rights reserved to the states and their people: the right to decide if their state was a free state or a slave state.
The Confederate constitution mandated that all states be slave states without exception.