Editing Wilmot Proviso (section)

==Background==
After an earlier attempt to acquire [[Republic of Texas|Texas]] by treaty had failed to receive the necessary two-thirds approval of the [[United States Senate|Senate]], the [[United States]] annexed the [[Republic of Texas]] by a joint resolution of [[United States Congress|Congress]] that required simply a majority vote in each house of Congress. President [[John Tyler]] signed the bill on March 1, 1845, a few days before his term ended.  As many expected, the annexation led to war with [[Mexico]].  After the [[Capture of New Mexico]] and [[Treaty of Cahuenga|California]] in the first phases of the war, the political focus shifted to how much territory would be acquired from Mexico.  The key to this was the determination of the future status of slavery in any new territory.

Both major political parties had labored long to keep divisive slavery issues out of national politics.  The Democrats had generally been successful in portraying those within their party attempting to push a purely sectional issue as extremists that were well outside the normal scope of traditional politics.<ref>Silbey (2005), p. 123.</ref> However, midway through [[James Knox Polk|Polk]]'s term, Democratic dissatisfaction with the administration was growing within the [[Martin Van Buren]], or [[Barnburner]], wing of the Democratic Party over other issues. Many felt that Van Buren had been unfairly denied the party's nomination in 1844 when southern delegates resurrected a convention rule, last used in 1832, requiring that the nominee had to receive two-thirds of the delegate votes.  Many in the North were also upset with the [[Walker tariff]] which reduced the tariff rates; others were opposed to Polk's veto of a popular river and harbor improvements bill, and still others were upset over the [[Oregon Treaty|Oregon settlement]] with [[United Kingdom|Great Britain]] where it appeared that Polk did not pursue the northern territory with the same vigor he used to acquire Texas. Polk was seen more and more as enforcing strict party loyalty primarily to serve southern interests.<ref>Morrison (1997), p. 42; Johannsen (1973), p. 202; Potter (1973), p. 22{{endash}}29.</ref>

[[File:Whig harmony.jpg|thumb|left|The Wilmot Proviso was seen as a stumbling block for presidential candidates, such as [[Zachary Taylor|Taylor]].]]
The [[Whig Party (United States)|Whigs]] faced a different scenario. The narrow victory of [[James K. Polk]] (Democrat) over [[Henry Clay]] (Whig) in the 1844 presidential election had caught the Southern Whigs by surprise.  The key element of this defeat, which carried over into the congressional and local races in 1845 and 1846 throughout the South, was the party's failure to take a strong stand favoring Texas annexation.  Southern Whigs were reluctant to repeat their mistakes on Texas, but, at the same time, Whigs from both sections realized that victory and territorial acquisition would again bring out the issue of slavery and the territories.  In the South in particular, there was already the realization, or perhaps fear, that the old economic issues that had defined the [[Second Party System]] were already dead. Their political goal was to avoid any sectional debate over slavery which would expose the sectional divisions within the party.<ref>Cooper (1978), p. 225{{endash}}229.</ref>

The [[Mexican–American War]] was seen by many as an effort to gain more territory for the establishment of [[Slave states and free states|slave states]]. It was popular in the South,<ref>''E.g.'', O'Sullivan's 1845 article [http://web.grinnell.edu/courses/HIS/f01/HIS202-01/Documents/OSullivan.html "Annexation"] {{Webarchive|url=https://web.archive.org/web/20051125043717/http://web.grinnell.edu/courses/HIS/f01/HIS202-01/Documents/OSullivan.html |date=November 25, 2005}}, ''United States Magazine and Democratic Review''.</ref> and much less so in the North,<ref>{{cite book|last=Gradert |first=Kenyon |title=Puritan Spirits in the Abolitionist Imagination |location=Chicago |publisher=The University of Chicago Press |year=2020 |page=108 |isbn=978-0-226-69402-3}}</ref> where opposition took many forms.  For example, [[Henry David Thoreau]] refused to pay his [[poll tax]], arguing that the money would be used to prosecute the war and gain slave territory.<ref>{{cite book|last=Rosenwald |first=Lawrence |url=http://thoreau.eserver.org/theory.html |title=The Theory, Practice and Influence of Thoreau's Civil Disobedience |editor-first=William |editor-last=Cain |year=2006 |chapter=A Historical Guide to Henry David Thoreau |location=Cambridge |publisher=Oxford University Press |archive-url=https://archive.today/20131014012153/http://thoreau.eserver.org/theory.html |archive-date=October 14, 2013}}</ref>