Which individual was one of the ardent secessionists in the U.S. Senate leading up to the Civil War?

Robert Toombs was a prominent figure in the U.S. Senate who passionately advocated for the secession of Southern states from the Union in the lead-up to the Civil War. As a Georgian politician and a staunch supporter of the Southern cause, Toombs's efforts reflected the intense sectional conflict and the desire for Southern states to assert their rights regarding slavery and state sovereignty. His status as a significant orator and leader among secessionists made him an influential figure during this tumultuous period.

Alexander Stephens, while a key Southern politician who served alongside Toombs, initially opposed secession and later became the Vice President of the Confederacy. Howell Cobb, though aligned with the secessionist movement, played more roles in military and governmental positions rather than being a vocal proponent in the Senate during the critical moments leading into the Civil War. Roswell King, meanwhile, was not a prominent political figure in the same capacity as Toombs and did not hold a position in the Senate, making him less relevant to the question regarding Senate leaders advocating for secession.