Why were southern politicians opposed to wilmot proviso?

The Wilmot Provision was a proposal to ban slavery in US territories acquired from Mexico. The conflict over the Wilmot Proviso was the major event that led to the American civil war. It was introduced by the congressman David Wilmot of Pennsylvania in 1846. It was passed in the house but failed in the senate because of the majority of southerners in the Senate. The southerners opposed this provision because they saw it as an attempt to destroy slavery and they were against the abolition of slavery. It was reintroduced in  February 1847. while it was again passed in the house it failed in the senate.

c.) the country needed a stronger central government.

they believed democracy was worth the fight