Despite Taylor 's unclear political affiliations and beliefs , and the Whig opposition to the Mexican – American War , the 1848 Whig National Convention nominated the popular general over party stalwarts such as Henry Clay and Daniel Webster . For vice president , the Whigs nominated Millard Fillmore , a New York Whig known for his moderate views on slavery . Incumbent President James K. Polk , a Democrat , honored his promise not to seek re-election , leaving his party 's nomination open . The 1848 Democratic National Convention rejected former President Martin Van Buren 's bid for a second term , instead nominating Senator Lewis Cass of Michigan . Van Buren broke from his party to lead the ticket of the Free Soil Party , which opposed the extension of slavery into the territories
1848 Democratic National Convention
1848 Democratic National Convention
1848 United States presidential election