Secretary of War Simon Cameron presented a long brief against relieving Sumter. Supporting the position of General Scott, Major Anderson, and other army officers, Cameron argued that the fort could only be relieved by a "large expedition of ships of war and troops." Even if Fox's plan worked, it would only provide provisions for one or two months. Since the fort must be abandoned sooner or later, he thought that "sooner it be done the better."
Cameron repeated Scott's argument that the time for a relief expedition had passed. With Charleston Harbor now a heavily armed camp, "it cannot now be done without the sacrifice of life and treasure not at all commensurate with the object to be attained." Even if relieved, the fort could do no damage to Confederate forces or Charleston, and would eventually fall to the enemy, anyway. Thus, "no practical benefit will result to the country or the government by accepting" Fox's proposal.
Bibliography: Lincoln, Works, eds. Nicolay and Hay, 6: 201-207.