The Free Soil Party was an abolitionist political party in the United States that was active from 1848 to 1854. The origins of the party lay with the explosive issue of slavery in the territories acquired during the Mexican-American War, as both the Democratic and Whig parties refused to take a positive stand against the extension of slavery into the territories. As a third party, the Free Soil Party was the immediate successor of the minor Liberty Party, which existed throughout the 1840s, and it adopted much of its platform and absorbed many of its leaders and supporters. Salmon P. Chase of Ohio led the Liberty Party into a merger with other more moderate abolitionist groups to form the Free Soilers in 1848.
The largest faction of the party was the anti-extentionists (led by Salmon P. Chase and Charles Sumner), who were not willing to interfere with slavery in the American South, but were willing to resist its expansion into the territories and its practice in Washington DC. The other faction was the abolitionist faction, led by William Lloyd Garrison, who sought an immediate uncompensated end to slavery everywhere.
The Free Soil Party was formed by the merger of several Libertyites, the liberal Democratic "Barnburners" of New York, other anti-slavery Democrats, and anti-slavery Whigs. In 1848, Martin Van Buren ran as the Free Soil Party candidate for president, and Charles Francis Adams Sr. was his running mate, winning 10.1% of the vote in a failed bid. The Compromise of 1850 reduced consciousness concerning slavery, but the Kansas-Nebraska Act of 1854 revived an interest in slavery, and the newer Republican Party was formed as the flagship of the abolitionist movement. In 1854, the Free Soil Party and the Whigs merged into the Republican Party.