During the period leading up to the American Civil War, several political, social, and economic factors contributed to the growing divide between the Northern and Southern states. One significant conflict arose over the issue of slavery, which was not only a moral dilemma but also deeply intertwined with economic interests and political power. A vital aspect that exacerbated tensions was the varying interpretations of constitutional rights regarding slavery and state sovereignty. Which of the following developments best encapsulates the pivotal shift in public sentiment towards the abolition of slavery in the years leading up to the Civil War?