(1846) Proposal in the U.S. Congress to prohibit the extension of slavery to the territories.
Offered by Rep. David Wilmot (1814–68) as an amendment to a bill that purchased territory from Mexico, it prohibited slavery in the new territory. The proviso provoked a national debate that reflected the growing sectional discord between North and South. Despite repeated attempts, the Wilmot Proviso was never passed by both houses of Congress. Nevertheless, the principle became a basic tenet of the Republican Party .