What did Abraham Lincoln argue at the Lincoln Douglas debate's gained national attention in spotlight?

During the Lincoln-Douglas debates in 1858, Abraham Lincoln argued against the expansion of slavery into the territories, emphasizing that it was morally wrong and posed a threat to the principles of democracy and equality. He contended that the nation could not endure permanently half slave and half free, advocating for the rights of African Americans and the importance of setting a moral precedent. Lincoln's articulate stance on these issues gained national attention, positioning him as a prominent figure in the growing anti-slavery movement and laying the groundwork for his future presidential campaign.