Wilmot Proviso
Whig opposition to the war grew after 1845, while some Democrats lost their initial enthusiasm. 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. Polk's request ignited opposition to the war, as Polk had never before made public his desire to annex parts of Mexico (aside from lands claimed by Texas). A freshman Democratic Congressman, David Wilmot of Pennsylvania, offered an amendment known as the Wilmot Proviso that would ban slavery in any newly acquired lands. The appropriations bill, including the Wilmot Proviso, passed the House with the support Northern Whigs and Northern Democrats, breaking the normal pattern of partisan division in congressional votes. Wilmot himself held anti-slavery views, but many pro-slavery Northern Democrats voted for the bill out of anger at Polk's perceived bias towards the South. The partition of Oregon, the debate over the tariff, and Van Buren's antagonism towards Polk all contributed to Northern anger. The appropriations bill, including the ban on slavery, was defeated in the Senate, but the Wilmot Proviso injected the slavery debate into national politics.