I'll let the southerners speak for themselves on the issue. Consider this from the New Orleans Bee, December 14, 1860:
"[The chief obstacle to reconciliation] is the absolute impossibility of revolutionizing Northern opinion in relation to slavery. Without a change of heart, radical and thorough, all guarantees which might be offered are not worth the paper on which they would be inscribed. As long as slavery is looked upon by the North with abhorrence; as long as the South is regarded as a mere slave-breeding and slave-driving community; as long as false and pernicious theories are cherished respecting the inherent equality and rights of every human being, there can be no satisfactory political union between the two sections."
"[F]alse and pernicious theories [about] the inherent equality ... of every human being"??? Sounds like the editors of the Bee don't believe Jefferson when he stated that "All men are created equal."
And of course, the gist of the editorial is that the Northerners must come around to the southern point of view on slavery or there can be no Union.
Slavery - Secession - Linkage.
This was common verbiage in the Slaver's organs and had been for a decade-long agitation for secession.