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 U. S. House Speaker , who emerged as the first dark horse nominee . 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
1844 Democratic National Convention
1844 Democratic National Convention
1844 United States presidential election