The 1844 United States presidential election was the 15th quadrennial presidential election, held from Friday, November 1 to Wednesday, December 4, 1844. Democrat James K. Polk defeated Whig Henry Clay in a close contest turning on the controversial issues of slavery and the annexation of the Republic of Texas. This is the only election where both major party nominees served as Speaker of the House at one point. President John Tyler's pursuit of Texas annexation divided both major parties. Annexation would geographically expand American slavery. It also risked war with Mexico while the United States engaged in sensitive possession and boundary negotiations with the Great Britain, which controlled Canada, over Oregon. Texas annexation thus posed both domestic and foreign policy risks. Both major parties had wings in the North and the South, but the possibility of the expansion of slavery threatened a sectional split in each party. Expelled by the Whig Party after vetoing key Whig legislation and lacking a firm political base, Tyler hoped to use the annexation of Texas to win re-election as an independent or at least to have decisive, pro-Texas influence over the election. The early leader for the Democratic nomination was former President Martin Van Buren, but his rejection of Texas annexation damaged his candidacy. Opposition from former President Andrew Jackson and most Southern delegations, plus a nomination rule change likely specifically aimed to block him, prevented Van Buren from winning the necessary two-thirds vote of delegates to the 1844 Democratic National Convention. The convention instead chose James K. Polk, former Governor of Tennessee and Speaker. He was the first successful dark horse for the presidency. Polk ran on a platform embracing popular commitment to expansion, often referred to as Manifest Destiny. Tyler dropped out of the race and endorsed Polk. The Whigs nominated Henry Clay, a famous, long-time party leader who was the early favorite but who conspicuously waffled on Texas annexation. Though a Southerner from Kentucky and a slave owner, Clay chose to focus on the risks of annexation while claiming not to oppose it personally. His awkward, repeated attempts to adjust and finesse his position on Texas confused and alienated voters, contrasting negatively with Polk's consistent clarity. Polk successfully linked the dispute with Britain over Oregon with the Texas issue. The Democratic nominee thus united anti-slavery Northern expansionists, who demanded Oregon, with pro-slavery Southern expansionists who demanded Texas. In the national popular