You’re off by a few generations. Introduction of slavery and the support of it by a corrupt DEMOCRAT Party was and is the problem. Today, the only people who want to (still) enslave anyone are Dems. Only the REPUBLICAN Party under Lincoln had as the top of its platform the ending of slavery in the territories. Neoconfederates just can’t deal with the simple truth that their section of the country not only believed in slavery, but put it in their constitution, not once, but thrice.
Democrats do not believe this any more today than they did 150 years ago.