Midway through Tyler 's presidency , the Democrats were badly divided , especially between followers of Calhoun and Van Buren . Former Vice President Richard Mentor Johnson of Kentucky , former Secretary of War Lewis Cass of Michigan , and Senator James Buchanan of Pennsylvania also loomed as contenders for the 1844 Democratic presidential nomination . By late 1843 , Van Buren had emerged as the front-runner for the Democratic presidential nomination , and Calhoun decided that he would not seek the nomination . As proponents of the annexation of Texas came to oppose his candidacy , Van Buren 's strength in the party diminished . At the 1844 Democratic National Convention , Van Buren failed to win the necessary super-majority of Democratic votes . It was not until the ninth ballot that the Democrats turned their sights to James K. Polk , a less prominent candidate who supported annexation . A protege of Andrew Jackson , Polk had hoped to win the vice presidential nomination prior to the convention , but Democratic delegates instead made Polk the first " dark horse " presidential nominee in U.S. history . Polk 's nomination pleased the followers of Calhoun , and they threw their support behind his candidacy rather than Tyler 's . Clay , meanwhile , had been nominated for president at the 1844 Whig National Convention
1844 Democratic National Convention
1844 Democratic National Convention
Presidency of John Tyler