Up and until December of 1860, the political disagreements and Congressional battles were about the balance of power between the agricultural South, and the Mercantilist North and Midwest.
Within six weeks, and due to the advent of a new tariff and a new political platform, the argument was now between the establishment Union and a progressive South on the verge of economic explosion.
The issue of slavery was now a non-issue for these people.
Add to that the superiority of the delivery system of the Mississippi that would destroy the Northeastern shipping system as well as the tariff schemes, and no wonder Governors, businessmen, and Congressmen were lined up at Lincoln's door to require him to stop the South.
No, there was no "argument".
Instead there was rebellion, insurrection, "domestic violence", invasion of Federal properties and eventually war against the United States, meaning treason for those who supported the Confederacy.
"Progressive South" in those days was a contradiction in terms, unless you wish to define protecting slavery as "progressive".
If so, it simply proves beyond reasonable doubt how much of a Democrat you really are.