In the debates he again put forth his famous utterance, "A house divided against itself cannot stand," with the explanation that in course of time either this country would become all slave territory or slavery would be restricted and placed in a position which would involve its final extinction.

In other words, Lincoln's position was similar to that of the conservative abolitionists.

As we know, Birney had given expression to a similar conviction of the impossibility of maintaining both liberty and slavery in this country, but Lincoln spoke at a time when the whole country had been aroused upon the great question; when it was still uncertain whether slavery would not be forced upon the people of Kansas; when the highest court in the land had rendered a decision which was apparently intended to legalize slavery in all Territories; and when the alarming question had been raised whether the next step would not be legalization in all the States.
Lincoln was a long-headed politician, as well as a man of sincere moral judgments.

He was defining issues for the campaign of 1860 and was putting Douglas on record so that it would be impossible for him, as the candidate of his party, to become President.

Douglas had many an uncomfortable hour as Lincoln exposed his vain efforts to reconcile his popular sovereignty doctrine with the Dred Scott decision.