Editing Martin Van Buren (section)

===Election of 1848===
[[File:Martin Van Buren daguerreotype by Mathew Brady circa 1849 - edit 1.jpg|thumb|upright=0.8|alt=Half-length photographic portrait of an elderly, balding man dressed in a dark coat, vest and cravat|[[Daguerreotype]] of Van Buren by [[Mathew Brady]], {{circa|1849–1850}}]]
Though he had previously helped maintain a balance between the [[Barnburners and Hunkers]], the two factions of the New York Democratic Party, Van Buren moved closer to the Barnburners after the 1844 Democratic National Convention.{{sfn|Niven|1983|p=543–544}} The split in the state party worsened during Polk's presidency, as his administration lavished patronage on the Hunkers.{{sfn|Niven|1983|pp=570–571}} In his retirement, Van Buren also grew increasingly opposed to slavery.<ref>{{cite book |last= Ferrell |first=Claudine L. |date=2006 |title=The Abolitionist Movement|url=https://books.google.com/books?id=mG_MNzwawSAC&pg=PA88 |location=Westport|publisher=Greenwood Press |page=88 |isbn=978-0-313-33180-0}}</ref>

As the [[Mexican–American War]] brought the debate over slavery in the territories to the forefront of American politics, Van Buren published an anti-slavery manifesto. In it, he refuted the notion that Congress did not have the power to regulate slavery in the territories, and argued the [[Founding Fathers]] had favored the eventual [[Abolitionism in the United States|abolition]] of slavery.{{sfn|Niven|1983|pp=567–570}} The document, which became known as the "Barnburner Manifesto", was edited at Van Buren's request by John Van Buren and [[Samuel Tilden]], both of whom were leaders of the Barnburner faction.{{sfn|Silbey|2002|pp=193–194}} After the publication of the Barnburner Manifesto, many Barnburners urged the former president to seek his old office in the [[1848 United States presidential election|1848 presidential election]].{{sfn|Niven|1983|pp=575–576}} The [[1848 Democratic National Convention]] seated competing Barnburner and Hunker delegations from New York, but the Barnburners walked out of the convention when Lewis Cass, who opposed congressional regulation of slavery in the territories, was nominated on the fourth ballot.{{sfn|Niven|1983|p=580}}

In response to the nomination of Cass, the Barnburners began to organize as a [[third party (United States)|third party]]. At a convention held in June&nbsp;1848, in [[Utica, New York]], the Barnburners nominated 65-year-old Van Buren for president.{{sfn|Niven|1983|pp=581–585}} Though reluctant to bolt from the Democratic Party, Van Buren accepted the nomination to show the power of the anti-slavery movement, help defeat Cass, and weaken the Hunkers.{{sfn|Niven|1983|pp=585–586}} At a convention held in [[Buffalo, New York]] in August&nbsp;1848, a group of anti-slavery Democrats, Whigs, and members of the abolitionist [[Liberty Party (United States, 1840)|Liberty Party]] met in the first national convention of what became known as the [[Free Soil Party]].{{sfn|Niven|1983|pp=587–589}}

The convention unanimously nominated Van Buren, and chose [[Charles Francis Adams Sr.|Charles Francis Adams]], son of late former President [[John Quincy Adams]] and grandson of late former President [[John Adams]], as Van Buren's running mate. In a public message accepting the nomination, Van Buren gave his full support for the [[Wilmot Proviso]], a proposed law that would ban slavery in all territories acquired from Mexico in the Mexican–American War.{{sfn|Niven|1983|pp=587–589}} Anti-slavery Whig orator [[Daniel Webster]], in his "Marshfield Speech", expressed skepticism, in terms that may have influenced Whig voters, about the sincerity of Van Buren's espousal of the anti-slavery cause:

{{blockquote|In Mr. Van Buren's anti-slavery professions, Mr. Webster had no confidence. He said pleasantly, but significantly, that "if he and Mr. Van Buren should meet under the Free-soil flag, the latter with his accustomed good-nature would laugh." He added, with a touch of characteristic humor, "that the leader of the Free-spoil party suddenly becoming the leader of the Free-soil party is a joke to shake his sides and mine."<ref name=Blaine>{{Cite web|url=https://www.gutenberg.org/files/21128/21128-8.txt|title=Twenty Years of Congress, Vol. 1 From Lincoln to Garfield, with a Review of the Events Which Led to the Political Revolution of 1860|first=James Gillespie|last=Blaine|website=gutenberg.org|access-date=October 18, 2021|archive-date=June 6, 2021|archive-url=https://web.archive.org/web/20210606222436/https://www.gutenberg.org/files/21128/21128-8.txt|url-status=live}}</ref>}}
Van Buren won no electoral votes, but finished second to Whig nominee [[Zachary Taylor]] in New York, taking enough votes from Cass to give the state—and perhaps the election—to Taylor.{{sfn|Manweller|2012|p=[https://books.google.com/books?id=yM7E2G0tAiwC&pg=PA271 271]}} Nationwide, Van Buren won 10.1% of the popular vote, the [[List of third party performances in United States presidential elections|strongest showing by a third-party presidential nominee]] up to that point in U.S. history.