The debate between Lincoln and Douglas was legendary. Lincoln was a pretty good debater, he asked Douglas what he would do if the people of the land voted slavery down, but the the Supreme Court says you can’t, who’s side would you be on? He said that the people should choose.
What Douglas said made him lose the election. He was fighting the lesser of two evils and lost, he chose the wrong side because now the south hated him. The Freeport Doctrine is the reason he lost.