David Wilmot – 1814-1868
Although he was a Democrat, this Pennsylvania congressman supported abolition, and proposed on August 8, 1846 a proviso (actually originated by Jacob Brinkerhoff of Ohio, but promoted by Wilmot) to outlaw slavery in any territory acquired from Mexico as a result of the U.S.-Mexican War. Wilmot attempted to attach the proviso to various bills, but it was always defeated. Nevertheless, its introduction gave birth to the Free Soil Party, which led to the founding of the antislavery Republican Party.