You have the speech given by the Vice President stating exactly that!
What part of the speech did you not understand?
The Pre-Civil War South rejected the principles of the DOI (as noted in Stephens speech)
The DOI was rejected because slavery in the Pre Civil War South was seen as a positive not a negative.
As Stephens himself notes regarding the Declaration generation, they had hoped to see the eventual end of slavery, hence, they made compromises regarding the Constitution.
The Pre Civil War South rejected the notion that all men were created equal and thus were of a different mind then the Southerners of Jefferson's day.
Facts are stubborn things.
Doesn't even make sense.