Who suggested that the south should secede from the union of an agreement could not be reached on slavery?

John C. Calhoun, a prominent Southern politician and advocate for states' rights, suggested that the South should secede from the Union if an agreement could not be reached regarding the issue of slavery. He believed that the federal government was infringing on the rights of Southern states and that secession was a legitimate response to protect their interests. Calhoun's ideas significantly influenced Southern attitudes leading up to the Civil War.