Martin Van Buren, President of the United States between 1837 and 1841, and chief architect of Jacksonian democracy, was the presumptive Democratic presidential contender in the spring of 1844. With Secretary of State John C. Calhoun withdrawing his bid for the presidency in January 1844, the campaign was expected to focus on domestic issues. All this changed with the Tyler treaty. Van Buren regarded the Tyler annexation measure as an attempt to sabotage his bid for the White House by exacerbating the already strained North-South Democratic alliance regarding slavery expansion. Calhoun's Packenham Letter would serve to spur Democrats of the South to the task of forcing the Northern wing of the party to submit to Texas annexation, despite the high risk of "aggressively injecting slavery into their political campaign over Texas."