The south threatened to from the union if their political interests were not met. western territories had not yet joined the union.

The south threatened to succeed from the union.

Secede.

The south threatened to leave the union as they did not want to be apart of a nation, or secede.

This was due to the fact that the South was pro-slavery while the North was anti-slavery and they also didn't want Abraham Lincoln to be elected president.

Hope this helps!

i confess that there are several parts of this constitution which i do not at present approve, but i am not sure i shall never approve them: for having lived long, i have experienced many instances of being obliged by better information or fuller consideration, to change opinions even on important subjects, which i once thought right, but found to be otherwise. it is therefore that the older i grow, the more apt i am to doubt my own judgment, and to pay more respect to the judgment of others.