Originally posted by Napoleon_VI
They did discuss it in the War of 1812.
Some radical Republicans discussed it prior to 1860 as well. I think it should be just as possible for New England to secede in response to a strongly sectional party being elected as was the deep South in real life. If Breckinridge been the only Democratic nominee in 1860 he might have won, and if he won on a platform of guaranteeing slavery in all the territories, strongly enforcing the Fugitive Slave Act throughout the North, and expanding southward, there would have been calls for seccession by radical abolitionists in New England. Maybe they would have been as successful as the Southern firebrands were in real life?
I don't think a USA less New England (and even more dominated by the South) would have fought to keep New England in the Union, though. Who needs those high-tarriff busybodies? So, no Civil War, hello "Southern Dream of a Carribean Empire,"* with the Old Northwest and the territories along for the ride.
And the UK would have to choose between an abolitionist New England that is an industrial rival but doesn't threaten European holdings in the Carribean and Central and South America and a slave-holding USA that provides a low-tarriff market for their industries but actively enforces the Monroe Doctrine at least, and at most considers Manifest Destiny to extend from Alaska to the Spanish Main. Sounds like fun!
* a great book by Robert May, (Univ Press of Florida, 2nd ed. 2002).
Edited to add cite.