Yes. See Article V, U.S. Constitution.
So, like others of our pro-Confederate geniuses, defenders of slavery in the South, you now presume to criticize Republicans for not abolishing slavery in the South quickly enough to suit you?
Did you "forget" that slavery was already abolished in the North?
Or is there some genuine, ahem, strategery here?
Is your real complaint, the genuine article of your belief, along with, say John Breckenridge, that the Union should have first declared war on the Confederacy (thus acknowledging its existence), then abolished slavery in Southern Union states (i.e., Kentucky, Maryland), while there was still opportunity for those states to secede & join the Confederacy?
I think I "get" this -- you're fantasizing how the Confederacy might have won their war, if only those dumb*ss Yankees could be bamboozled into more dumb*ass mistakes.
Hey, nice try!