Either the opponents of slavery, will arrest the further spread of it, and place it where the public mind shall rest in the belief that it is in the course of ultimate extinction; or its advocates will push it forward, till it shall become alike lawful in all the States, old as well as new — North as well as South.
Have we no tendency to the latter condition?
Let any one who doubts, carefully contemplate that now almost complete legal combination — piece of machinery so to speak — compounded of the Nebraska doctrine, and the Dred Scott decision.

The House Divided speech (1858)