Editing Whig Party (United States) (section)

=== Polk and the Mexican–American War, 1845–1849 ===
{{Further|Presidency of James K. Polk}}
[[File:Zachary Taylor restored and cropped.jpg|thumb|upright|[[Zachary Taylor]] served in the [[Mexican–American War]] and later won the 1848 presidential election as the Whig nominee.]]
[[File:Treaty of Guadalupe Hidalgo.png|thumb|The United States settled the Texas-Mexico border and acquired portions of seven current states in the [[Treaty of Guadalupe Hidalgo]]. Portions of present-day Arizona and New Mexico were later acquired in the 1853 [[Gadsden Purchase]].]]

In the final weeks of Tyler's presidency, a small group of Southern Whigs joined with congressional Democrats to pass a joint resolution providing for the annexation of Texas, and Texas subsequently became a state in 1845.<ref>Holt (1999), pp. 220–221.</ref> Following the annexation of Texas, Polk began preparations for a potential war with [[Mexico]], which still regarded Texas as a part of its republic and contended that Texas's true southern border was the [[Nueces River]] rather than the [[Rio Grande]].<ref name=Merry188189>Merry (2009), pp. 188–189.</ref> After a skirmish known as the [[Thornton Affair]] broke out on the northern side of the Rio Grande,<ref name=merry240242>Merry (2009), pp. 240–242.</ref> Polk called on Congress to declare war against Mexico, arguing that Mexico had invaded American territory by crossing the Rio Grande.<ref name=merry244245>Merry (2009), pp. 244–245.</ref>

Many Whigs argued that Polk had provoked war with Mexico by sending a force under General [[Zachary Taylor]] to the Rio Grande, but only a minority of Whigs voted against the declaration of war as they feared that opposing the war would be politically unpopular.<ref>Holt (1999), p. 233.</ref> Polk received the declaration of war against Mexico and also pushed through the restoration of the Independent Treasury System and a bill that reduced tariffs; opposition to the passage of these Democratic policies helped to reunify and reinvigorate the Whigs.<ref>Holt (1999), pp. 233–234.</ref>

In August 1846, Polk asked Congress to appropriate $2&nbsp;million (~${{Format price|{{Inflation|index=US-GDP|value=2000000|start_year=1846}}}} in {{Inflation/year|US-GDP}}) in hopes of using that money as a down payment for the purchase of California in a treaty with Mexico.<ref name=merry283285>Merry (2009), pp. 283–285.</ref> Democratic Congressman [[David Wilmot (politician)|David Wilmot]] of Pennsylvania offered an amendment known as the [[Wilmot Proviso]], which would ban slavery in any newly acquired lands.<ref name=merry286289>Merry (2009), pp. 286–289.</ref> The Wilmot Proviso passed the House with the support of both Northern Whigs and Northern Democrats, breaking the typical pattern of partisan division in congressional votes, but it was defeated in the Senate.<ref>McPherson, pp. 53–54.</ref>

Nonetheless, clear divisions remained between the two parties on territorial acquisitions, as most Democrats joined Polk in seeking to acquire vast tracts of land from Mexico, but most Whigs opposed territorial growth.<ref>Holt (1999), pp. 252–253.</ref> 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.<ref name=merry424426>Merry (2009), pp. 424–426.</ref> Despite Whig objections to the acquisition of Mexican territory, the treaty was ratified with the support of a majority of the Democratic and Whig senators; Whigs voted for the treaty largely because ratification brought the war to an immediate end.<ref>Holt (1999), pp. 310–311.</ref>

[[File:Whig primary 1848d.jpg|thumb|A political cartoon satirizing the candidacy of either [[Zachary Taylor]] or [[Winfield Scott]] in the [[1848 United States presidential election|1848 presidential election]]]]

During the war, Whig leaders like [[John J. Crittenden]] of Kentucky began to look to General Taylor as a presidential candidate, hoping the party could run on Taylor's personal popularity rather than economic issues.<ref>Holt (1999), pp. 246–247, 269.</ref> Taylor's candidacy faced significant resistance in the Whig Party due to his lack of public commitment to Whig policies and his association with the Mexican–American War.<ref>Holt (1999), pp. 258–260.</ref> In late 1847, Clay emerged as Taylor's main opponent for the Whig nomination, appealing especially to Northern Whigs with his opposition to the war and the acquisition of new territory.<ref>Holt (1999), pp. 277–280.</ref>

With strong backing from slavery-state delegates, Taylor won the presidential nomination on the fourth ballot of the [[1848 Whig National Convention]].<ref>Holt (1999), pp. 323–326.</ref> The Whigs nominated Millard Fillmore of New York, a pro-Clay Northerner, for vice president.{{sfn|Smith|1988|pp=22–23}} Anti-slavery Northern Whigs disaffected with Taylor joined with Democratic supporters of Martin Van Buren and some members of the Liberty Party to found the new [[Free Soil Party]]; the party nominated a ticket of Van Buren and Whig [[Charles Francis Adams Sr.]] and campaigned against the spread of slavery into the territories.<ref>Holt (1999), pp. 333–334, 339.</ref>

The Whig campaign in the North received a boost when Taylor released a public letter in which he stated that he favored Whig principles and would defer to Congress after taking office, thereby reassuring some wavering Whigs.<ref>Holt (1999), p. 361.</ref> During the campaign, Northern Whig leaders touted traditional Whig policies like support for infrastructure spending and increased tariff rates,<ref>Holt (1999), p. 365.</ref> but Southern Whigs largely eschewed economic policy, instead emphasizing that Taylor's status as an enslaver meant that he could be trusted on the issue of slavery more so than Democratic candidate [[Lewis Cass]] of Michigan.<ref>Holt (1999), pp. 356–357.</ref> Ultimately, Taylor won the election with a majority of the electoral vote and a plurality of the popular vote. Taylor improved on Clay's 1844 performance in the South and benefited from the defection of many Democrats to Van Buren in the North.<ref>Holt (1999), pp. 368–370.</ref>