Free Soil Party

The Free Soil Party, also called the Free Democratic Party or the Free Democracy, was a political party in the United States from 1848 to 1854, when it merged into the Republican Party. The party was focused on opposing the expansion of slavery into the western territories of the United States. The 1848 presidential election took place in the aftermath of the Mexican–American War and debates over the extension of slavery into the Mexican Cession. After the Whig Party and the Democratic Party nominated presidential candidates who were unwilling to rule out the extension of slavery into the Mexican Cession, anti-slavery Democrats and Whigs joined with members of the Liberty Party (an abolitionist political party) to form the new Free Soil Party. Running as the Free Soil presidential candidate, former President Martin Van Buren won 10.1 percent of the popular vote, the strongest popular vote performance by a third party up to that point in U.S. history.

Though Van Buren and many other Free Soil supporters rejoined the Democrats or the Whigs after the 1848 election, Free Soilers retained a presence in Congress over the next six years. Led by Salmon P. Chase of Ohio, John P. Hale of New Hampshire, and Charles Sumner of Massachusetts, the Free Soilers strongly opposed the Compromise of 1850, which temporarily settled the issue of slavery in the Mexican Cession. Hale ran as the party's presidential candidate in the 1852 presidential election, taking just under five percent of the vote. The 1854 Kansas–Nebraska Act repealed the long-standing Missouri Compromise and outraged many Northerners, contributing to the collapse of the Whigs and spurring the creation of a new, broad-based anti-slavery Republican Party. Most Free Soilers joined the Republican Party, which emerged as the dominant political party in the United States in the Third Party System (1856–1894).

Though William Lloyd Garrison and most other abolitionists of the 1830s had generally shunned the political system, a small group of abolitionists founded the Liberty Party in 1840. The Liberty Party was a third party dedicated to the immediate abolition of slavery. The Liberty Party nominated James G. Birney for president and Thomas Earle for vice president in the 1840 presidential election. Months after the 1840 election, the party re-nominated Birney for president, established a national party committee, and began to organize at the state and local level. Support for the party grew in the North, especially among evangelical former Whigs in New England, upstate New York, Michigan, and Ohio's Western Reserve. Other anti-slavery Whigs like John Quincy Adams remained within the Whig Party, but increasingly supported anti-slavery policies like the repeal of the gag rule, which prevented the House of Representatives from considering abolitionist petitions. Meanwhile, long-time abolitionist leaders like Lewis Tappan became increasingly open to working within the political system. In a reflection of the rise of anti-slavery sentiment, several Northern states passed personal liberty laws that forbid state authorities from cooperating in the capture and return of fugitive slaves.

Beginning in May 1843, President John Tyler made the annexation of Texas his key priority. Most leaders of both parties opposed opening the question of annexation in 1843 due to their fear of stoking the debate over slavery; the annexation of Texas was widely viewed as a pro-slavery initiative because it would add another slave state to the union. Nonetheless, in April 1844, Secretary of State John C. Calhoun reached a treaty with Texas providing for the annexation of that country. Henry Clay and Martin Van Buren, the two front-runners for the major party presidential nominations in the 1844 presidential election, both announced their opposition to annexation, and the Senate blocked the treaty. To the surprise of Clay and other Whigs, the 1844 Democratic National Convention rejected Van Buren in favor of James K. Polk, and approved a platform calling for the acquisition of both Texas and Oregon Country. Polk went on to defeat Clay in a close election, taking 49.5 of the popular vote and a majority of the electoral vote. The number of voters casting a ballot for Birney increased tenfold from 6,200 in 1840 (0.3 percent of popular vote) to 62,000 (2.3 percent of the popular vote) in 1844.

Following the annexation of Texas in 1845, President Polk began preparations for a potential war with Mexico, which still regarded Texas as a part of its republic. After a skirmish known as the Thornton Affair broke out on the northern side of the Rio Grande, Polk convinced Congress to declare war against Mexico. Though most Democrats and Whigs initially supported the war, Adams and some other anti-slavery Whigs attacked the war as a "Slave Power" plot designed to expand slavery across North America. Meanwhile, former Democratic Representative John P. Hale had defied party leaders by denouncing the annexation of Texas, causing him to lose re-election in 1845. Hale joined with anti-slavery Whigs and the Liberty Party to create a new party in New Hampshire, and he won election to the Senate in early 1847. In New York, tensions between the anti-slavery Barnburner and the conservative Hunker factions of the Democratic Party rose, as the Hunkers allied with the Whigs to defeat the re-election campaign of Democratic Governor Silas Wright.

In August 1846, Polk asked Congress to appropriate $2 million (~$62.3 million in 2024) in hopes of using that money as a down payment for the purchase of Alta California in a treaty with Mexico. During the debate over the appropriations bill, Democratic Representative David Wilmot of Pennsylvania offered an amendment known as the Wilmot Proviso, which would ban slavery in any newly acquired lands. Though broadly supportive of the war, Wilmot and some other anti-slavery Northern Democrats had increasingly come to view Polk as unduly favorable to Southern interests, partly due to Polk's decision to compromise with Britain over the partition of Oregon. Unlike some Northern Whigs, Wilmot and other anti-slavery Democrats were largely unconcerned by the issue of racial equality, and instead opposed the expansion of slavery because they believed the institution was detrimental to the "laboring white man." The Wilmot Proviso passed the House with the support of both Northern Whigs and Northern Democrats, breaking the normal pattern of partisan division in congressional votes, but it was defeated in the Senate, where Southerners controlled a proportionally higher share of seats. Several Northern congressmen subsequently defeated an attempt by President Polk and Senator Lewis Cass to extend the Missouri Compromise line to the Pacific.

In February 1848, Mexican and U.S. negotiators reached the Treaty of Guadalupe Hidalgo, which provided for the cession of Alta California and New Mexico. Though many senators had reservations about the treaty, the Senate approved it in a 38-to-14 vote in February 1848. Senator John M. Clayton's effort to reach a compromise over the status of slavery in the territories was defeated in the House, ensuring that slavery would be an important issue in the 1848 election.

Led by John Van Buren, the Barnburners bolted from the 1848 Democratic National Convention after the party nominated a ticket consisting of Senator Lewis Cass of Michigan and former Representative William O. Butler of Kentucky; Cass and Butler had both opposed the Wilmot Proviso. Shortly after the Democrats nominated Cass, a group of Whigs made plans for a convention of anti-slavery politicians and activists in case the 1848 Whig National Convention nominated General Zachary Taylor of Louisiana for president. With the strong backing of slave state delegates, Taylor defeated Henry Clay to win the Whig presidential nomination. For vice president, the Whigs nominated Millard Fillmore of New York, a conservative Northerner. The nomination of Taylor, a slaveholder without any history in the Whig Party, spurred anti-slavery Whigs to go through with their convention, which would meet in Buffalo, New York, in August. A faction of the Liberty Party led by Salmon P. Chase agreed to attend the convention, though another faction of the party, led by Gerrit Smith, refused to consider merging with another party.