The Free Soil Party was a political party in the United States organized in 1848, with the main purpose of opposing the extension of slavery into the territories of the United States, as well as abolishing slavery itself.

The party evolved from abolitionists in the Democratic and Whig parties. Their first party convention was in Buffalo, New York, where they nominated former President Martin Van Buren with Charles Francis Adams as Vice President for their ticket. The two main party leaders were Salmon P. Chase and John P. Hale.

The Compromise of 1850 also helped the party to gain supporters who feared slavery was spreading and wanted to stop it. By 1854, most Free-Soilers joined the Republican party because of its strength and anti-slavery sentiments. The Kansas-Nebraska Act and the Dred Scott case also strengthened the views of abolitionists, although they were now members of the Republican party.

The Free Soil candidates ran on the platform declaring "...we inscribe on our banner, 'Free Soil, Free Speech, Free Labor and Free Man,' and under it we will fight on and fight ever, until a triumphant victory shall reward our exertions."

They also called for a homestead law and a tariff for revenue only. The Free Soil Party attracted mainly abolitionists from the North and other free states. Their main support came from the state of New York, though other states also had representatives. They came from parties such as the Liberty Party, the anti-slavery Whigs, and the Barnburners, a radical faction of the New York Democrats.

The Free Soil Party in its prime was a very notable third party. It was more successful than most, as it had two Senators and fourteen Representatives sent to the thirty-first Congress. Their presidential nominee in 1848, Martin Van Buren, received 291,616 votes against Zachary Taylor of the Whigs and Lewis Cass of the Democrats, although he received no electoral votes.

The strength of the party, however, was its representation in Congress. The sixteen elected officials were able to have an influence despite being a small group. It was hard for the party to achieve much success because it competed with the Republicans, who also believed in abolition, and the two eventually merged.

See also: List of political parties in the United States

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The Free Soil Party was a short-lived United States political party that existed in the first part of the 19th century. The party was formed around the Wilmot Proviso, a piece of legislation requiring that all territory taken from Mexico in the Mexican-American war be free from slavery. Although the Wilmot Proviso ultimately failed when New Mexico and Utah were opened to the possibility slavery based on popular soveregnty in the Compromise of 1850, it caused a group of Northern politicians to break off and form their own party. In the election of 1848 the Free Soilers nominated former President of the United States Martin van Buren for president and although they won no electoral votes, did receive a significant minority of the popular vote. With the dissolution of the Whig party following the Kansas-Nebraska Act, many northern Whigs combined with former Free-Soilers and northern Democrats to form the Republican party, which advocated a free-soil platform without retaining the name Free-Soilers.