The Kansas-Nebraska Act had been a divisive issue for the Democratic Party. In 1854, the Kansas-Nebraska Act passed to allow the two new territories hold a popular vote to decide whether slavery would be legal in the territory. This idea was proposed by members of the Democratic Party. The Act resulted in a small but deadly civil war, which became known as Bleeding Kansas, and was a precursor to the American Civil War.
The Democratic Party turned on President Franklin Pierce, who had signed the act. Pierce became the first president in U.S. history that attempted to seek reelection and was denied by his party. Further, the Democratic Party used the slogan "Anybody but Pierce" for the 1856 election. Instead, the party chose James Buchanan, an ambassador to the United Kingdom, who warned the public that a Republican president would lead the country into civil war. His running mate was John C. Breckinridge from Kentucky.
Republican candidate John C. Fremont campaigned against the expansion of slavery, and took a stand against the Kansas-Nebraska Act. The party chose William Dayton to be his running mate, over future President Abraham Lincoln. The Republican Party had formed to replace the Whig Party, which itself dissolved because of disagreements within the party over the issue of slavery. The Republicans opposed slavery and especially its expansion into new territories.
A third party, known as the Know-Nothings, or the American Party, formed in an attempt to become the second major political party in the United States, and to oppose the Democratic Party. The Know-Nothings focused their campaign on anti-immigration, choosing to ignore the issue of slavery entirely. Many candidates stepped up and attempted to earn the party nomination, but the Know-Nothings ultimately chose former President Millard Fillmore to represent the party. Fillmore had previously served as president after the death of President Zachary Taylor in 1850.
The Know-Nothing Party was fairly successful in the 1856 election, securing a number of electoral votes and about 20 percent of the popular vote. James Buchanan won the election with 174 electoral votes, but only received about 45 percent of the popular vote. Fremont came in just behind, with 114 electoral votes.