The difference then was that a new party built on the principle of opposing slavert had already appeared to replace the Whigs. It gained instant popularity. So far, no such party has appeared.
But just as slavery was declared the reason for the Civil War, it was not the reason for the start. Lincoln changed the narrative when he was losing the original reason. The Whigs dug their own grave before 1854, and we are seeing the same befall today’s Republicans. This was a watershed moment in our history.