[Ditto]

Lincoln’s strategy relied on the economic principles of supply and demand. He believed that if he could prevent the expansion of slavery into the federal territories and prevail upon state legislatures, beginning with the northern-most slave states, to accept gradual, compensated emancipation, the demand for slaves would fall while the supply would increase in the deep south. The combined effect would be to reduce the value of slave property. By thus “shrinking” slavery, he would make it uneconomical and once again place it back on the eventual road to extinction that he believed the Founders had envisioned.

This is key to understanding the causes of the Civil War. If Lincoln had his way and stopped expansion, the slave system would have collapsed on itself, and states would have been forced to end on their own.

[AmishDude]

It's even simpler than that. If the Republican party platform had been adopted, no new slave states would have lead to slavery having minority support in the Senate. And back then a filibuster couldn't be wielded willy-nilly. All business stopped.