The Emancipation Proclamation wasn’t an immediate favorite among Lincoln’s cabinet members. Edwin Stanton, the secretary of war, and Edward Bates, the attorney general, did favor immediate publication. Interior Secretary Caleb Smith considered resigning over it.
Postmaster General Montgomery Blair thought it would alienate the border states.
Three cabinet members supported it with reservations — Gideon Welles, secretary of the Navy, Treasury Secretary Salmon P. Chase and Secretary of State William H. Seward.
Source: Lincoln: America’s Greatest President at 200, Smithsonian Enterprises