The Republican Party formed in 1854 to oppose the extension of slavery. Many of the people who joined the new party were "Conscience Whigs," northern Whigs dissatisfied with their party's attempts to restrain slavery's growth.
Southern Whigs who supported slavery had long fought with northern Whigs who opposed the institution, but the party remained together through the strong personalities of its leaders and agreement on other issues. However, the Kansas-Nebraska Act of 1854, which gave territories the right to vote on whether to allow slavery, ripped the Whigs apart. A group of slavery opponents began meeting in 1854 to form a new party, and on March 20, 1854, they formed the Republican Party.
Although opposition to the expansion to slavery was their primary organizing issue, they also supported a number of related policies. They believed in giving western land to American farmers instead of selling it to pro-slavery plantation owners. Supporters of the new party also believed that a free market in labor encouraged civic virtue and economic growth. This new party attracted disgruntled northern Whigs, northern anti-slavery Democrats and members of the Free Soil and American Parties.
Though the Republicans did not win the 1856 presidential election, their nominee John C. Fremont did win 11 northern states. Four years later, the Republicans nominated Abraham Lincoln. Though he promised only to stop the expansion of slavery, the southern states seceded. This secession caused the Civil War, which in turn led to the entire abolition of slavery in the United States.