Do you not agree that the Democrats split, because Douglas would not repudiate "The Freeport Doctrine" and that the Southern Democrats were pushing for a Constitutional protection of slavery in the territories? In other words, the South would not accept "Popular Sovereignty" or the right of the states to decide by their electorate whether they would be free or slave and wanted to force the new territories to enter as slave or free states by decree.
The Mexican Secession?
William Lowndes Yancey?
The Alabama Platform?
Jim