Trouble is there are too many individual States split down the middle here. California and Arizona, probably Montana and Missouri, likely others would be divided. Stridently divided, sometimes within families. Much like the Civil War (see Missouri circa 1860-65). Hell, Idaho would prefer to be in the South, aligned with Alabama and Mississippi.
Besides, what makes you think any liberal would give enough of a crap about "ignorant nutjob secessionists Southerns and such"? Let 'em go, might be the predominate attitude.