Free Soil Party
Following the Mexican War, debate over the expansion and/or existence of slavery intensified. Factions appeared in both major American political parties opposing slavery's expansion westward. In the Whigs, this group was known as the "conscience Whigs" while those within the Democratic Party were known as "free soil Democrats." When neither party demonstrated a strong anti-slavery stance through their 1848 presidential nominations, some members of these factions defected and, along with members of the then-defunct Liberty Party, formed the Free Soil Party. The party held its first national convention in Buffalo, New York, that same year and nominated Martin Van Buren as its presidential candidate. Their platform, written by Benjamin F. Butler and Salmon P. Chase, most notably called for an end to slavery's expansion and the abolition of slavery in the District of Columbia. Van Buren did not win a single electoral vote but the party proved significantly more popular than its forebear, the Liberty Party, had four years earlier. After the election, the party became a very loose organization and began to fracture during the debates over the Compromise of 1850. It nominated John P. Hale as its 1852 presidential nominee but the party and its support-base were much diminished by that time. The remaining Free Soilers, especially Chase, became key players in the establishment of the Republican Party in 1856 and most eventually joined that new organization.
Eric D. Daniels, "Free Soil Party," The Oxford Companion to United States History, ed. by Paul S. Boyer (New York: Oxford University Press, 2001), 292-93; Jonathan H. Earle, Jacksonian Antislavery and the Politics of Free Soil, 1824-1854 (Chapel Hill: University of North Carolina Press, 2004); John R. Mayfield, Rehearsal for Republicanism: Free Soil and the Politics of Anti-Slavery (Port Washington, NY: Kennikat, 1980).