Who articulated the principle of "popular sovereignty" regarding slavery?

The principle of "popular sovereignty" regarding slavery was articulated primarily by Stephen A. Douglas. This concept suggested that the residents of a territory should have the right to decide whether to allow slavery or not, effectively allowing the people living in a region to determine their own laws regarding this issue. Douglas introduced this idea as a way to address the contentious issue of slavery’s expansion into the territories of the United States during the debates leading up to the Civil War. His support for popular sovereignty was prominently featured in the Kansas-Nebraska Act of 1854, which allowed the new territories to decide on the legality of slavery based on the wishes of their inhabitants.

Douglas's approach aimed to reduce national tensions surrounding slavery by pushing the decision-making power to the states and territories rather than having it dictated by federal legislation. This framing of the slavery issue reflected the democratic ideals of self-governance but also led to significant conflict and violence, notably in "Bleeding Kansas," as pro-slavery and anti-slavery forces clashed in the territories.