William B. Skelton, "Stanton, Edwin McMasters," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00942.html.
When the Democratic party split on the sectional issue in 1860, Stanton followed Buchanan and Black in supporting John C. Breckinridge, the presidential nominee of the southern Democrats, because he considered Breckinridge the only candidate capable of preserving the Union. During a cabinet shake-up in December 1860, Black became secretary of state, and Buchanan appointed Stanton to replace him as attorney general. Throughout the closing months of Buchanan's term, Stanton strove forcefully to preserve the Union. In the cabinet, he and Black constantly pressured the vacillating president to adopt a strong position against secession and to retain control of Fort Sumter and other forts along the southern coastline. Moreover, Stanton secretly passed information on cabinet deliberations to Senator William H. Seward and other Republicans in Congress. During his brief tenure as attorney general, Stanton did as much as anyone in the administration to stiffen Buchanan's stand and resist the secessionist surge.