Why was the compromise difficult for North and South?

The Crittenden Compromise was perhaps the last-ditch effort to resolve the secession crisis of 1860-61 by political negotiation. Authored by Kentucky Senator John Crittenden (whose two sons would become generals on opposite sides of the Civil War) it was an attempt to resolve the crisis by addressing the concerns that led the states of the Lower South to contemplate secession. As such, it gives a window into what the politicians of the day thought the cause of the crisis to be.