Any fight from the national government would be more of a whimper. A few conservative states sending a short sweet letter on state letterhead would be all it'd take. Any chest pounding from D.C. could be ignored. Seriously, what could the Hill do? Nothing, zilch, nada, zero. Send in the military? Really? That'd go down like a rock to the world and would be a loud resounding message to the remaining states that states' rights is dead.
Oddly enough, this is exactly what southerners said before the last secession. In fact, one southern senator stated that all the blood shed over secession wouldn't fill a lady's thimble.
He may have been right, but it would have taken one really large thimble.