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Free-Soil Party was a political party in the United States that existed for six years from 1848 to 1854 and opposed the extension of slavery to new territories. It then became a part of the Republican Party.

Explanation:

The political party officially formed during presidential elections in 1848, but the prerequisites for its establishment were set two years before by David Wilmot. Back then he introduced Wilmot Proviso to the Congress, a document that proposed prohibition of slavery on the new territories acquired by the United States after the Mexican war. Even though the proposal failed in Congress, it managed to become the ideological basis for the new political party.

In 1848, Whigs, delegates from 17 states, representing Liberty Party, and an antislavery faction of Democratic party gathered together in Buffalo to discuss their strategy. It was also the time when they came up with the historic slogan “Free Soil, Free Speech, Free Labor, and Free Men”. This democratic in modern terms motto draw many representatives of the workforce to the newly established party, mostly those were small farmers, merchants, and mill workers.

Nonetheless, free-soilers did not fight against racial discrimination or the abolition of slavery in all the states. Instead, they were advocating for its non-extension to new territories, though they did start leaning toward denouncing slavery by 1852. Free-Soil Party failed to get its candidate through presidential elections in 1848, but it became the forerunner of the Republican party that used the same platform throughout the 1850s.