Dramatic events preceding the election of 1856 altered the political landscape of American politics. Franklin Pierce had been a weak president whom most historians characterize as having been a tool of extreme southern politicians. He supported various expansionist schemes that accomplished little beyond poisoning the political world. Worse still was Pierce's decision to support Stephen A. Douglas's Kansas-Nebraska Act, a bill which organized the territories of Nebraska and Kansas and explicitly repealed the provision of the Missouri Compromise that prohibited the expansion of slavery to the northwest. Passage of the Kansas-Nebraska Act was one of the great catastrophes in American political history. A storm of outrage crested in the North, where the antislavery provision of the Missouri Compromise was regarded as practically part of the Constitution. Sectionalism was reborn and was exacerbated when free soil and proslavery settlers began battling for control of the territorial legislature in Kansas. In the resulting turmoil, the Whig party ceased to be a national organization, as southern Whigs began to defect to the Democrats and to the nativist American party. The Democratic party was increasingly controlled by southerners, as northern Democrats who backed the Kansas-Nebraska Act were defeated at the polls, while others defected to an anti-Nebraska coalition that formed in 1854.
The anti-Nebraska political coalition was composed of former members of the various political parties disaffected with the Kansas-Nebraska Act: Democrats, Whigs, nativists of the American party, abolitionists and free soilers from the remnants of the Liberty and Free Soil parties. These disparate groups were united in their opposition to the expansion of slavery as countenanced in the Kansas-Nebraska Act. In 1854, they began to call themselves the Republican party, and they formed a national organization early in 1856.
The election of 1856 pitted the new Republican party against the Democrats and a presidential candidate backed by the nativist American party and what was left of the old Whig party. Republicans nominated famed explorer and political novice John C. Frémont and approved a platform that opposed the expansion of slavery. Democrats abandoned the unpopular incumbent Franklin Pierce and chose veteran politician James Buchanan. He had the virtue of having been out of the country as minister to Great Britain while the controversy raged over the Kansas-Nebraska Act. Former president Millard Fillmore was the candidate of the nativists and Whigs.
The ongoing sectional tension shaped the campaign and the election outcome. Frémont and the Republican party did not even appear on the election ballots in most southern states, and many southern politicians vowed that their states would secede if Frémont were elected. These threats prompted many former Whigs and others of a conservative mindset to throw their support to Buchanan and the Democrats as the sole alternative to the catastrophe of disunion.
Buchanan triumphed on a tide of these sentiments, but the Republicans showed surprising strength for a new party. Though they had no presence in the South, Republicans won all but five northern states, and their vote totals revealed that if they could win over Pennsylvania and Illinois in 1860 while retaining the states they won in 1856, they would take the presidency. Such an outcome would place the nominee of a purely sectional party in the White House, an event that southerners had promised would prompt secession.