What doctrine did Douglas lose support in the south?

Stephen A. Douglas lost support in the South primarily due to his endorsement of the Freeport Doctrine, which suggested that territories could effectively exclude slavery by not adopting local laws to protect it. This position alienated Southern Democrats who believed in the necessity of protecting slavery in all territories. Additionally, his failure to fully align with pro-slavery factions during the contentious debates over the Kansas-Nebraska Act further diminished his standing in the Southern states. As a result, Douglas struggled to maintain his influence among Southern leaders and voters.