Wilmot Proviso
In August 1846, Polk asked Congress to appropriate $2 million in hopes of using that money as a down payment for the purchase of California in a treaty with Mexico. Democratic Congressman David Wilmot of Pennsylvania offered an amendment known as the Wilmot Proviso, which would ban slavery in any newly acquired lands. The Wilmot Proviso passed the House with the support of both Northern Whigs and Northern Democrats, breaking the normal pattern of partisan division in congressional votes, but it was defeated in the Senate.