The incumbent President John Tyler, formerly vice-president, had assumed the presidency upon the death of William Henry Harrison in 1841. Tyler, a Whig in name only, emerged as a states' rights advocate committed to slavery expansion in defiance of his party's principles. After he vetoed the Whig domestic legislative agenda, he was expelled from his own party on September 13, 1841. Politically isolated, but unencumbered by party restraints, Tyler aligned himself with a small faction of Texas annexationists in a bid for election to a full term in 1844.