The Barnburners opposed the extension of slavery, expanding public debt, and the power of the large corporations. They were led by former president Martin Van Buren and his son John, and in the 1848 presidential election they bolted from the party, refusing to support presidential nominee Lewis Cass, and instead joining with other anti-slavery groups, predominantly the Abolitionist Liberty Party (United States) and some anti-slavery Whigs in New England and the upper Midwest, to form the Free Soil Party, which would nominate the elder Van Buren for president.
Their opponents, the conservative Hunkers, favored minimizing the slavery issue, internal improvements, and state banks. The term hunker was derived from someone who "hunkers" (hankers) after a political office. Following the 1848 election, the Hunkers themselves split over the question of reconciliation with the Barnburners, with the Softs, led by William L. Marcy, favoring reconciliation, and the Hards, led by Daniel S. Dickinson, opposing it. This split would be exacerbated following the 1852 presidential election, when disputes over patronage led to an even broader split between Hards and Softs, and helped lead to the defeat of the Soft governor, Horatio Seymour for re-election in 1854.
The Hunkers wanted the status quo within the party in terms of the party's relationship between government and business. They supported the Southern Democrats.
The Barnburners were the reform faction because they were not in control of the party. They wanted to reform the system of party patronage. They broke with the Hunkers and supported the abolitionists. Eventually they ditched the party then they joined the conscience Whigs and the Free Soil Party.