Cass resigned as governor in 1831 to accept appointment as Secretary of War under Andrew Jackson . As Secretary of War , he helped implement Jackson 's policy of Indian removal . After serving as ambassador to France from 1836 to 1842 , he unsuccessfully sought the presidential nomination at the 1844 Democratic National Convention ; a deadlock between supporters of Cass and former President Martin Van Buren ended with the nomination of James K. Polk . In 1845 , the Michigan Legislature elected Cass to the Senate , where he served until 1848 . Cass 's nomination at the 1848 Democratic National Convention precipitated a split in the party , as Cass 's advocacy for popular sovereignty alienated the anti-slavery wing of the party . Van Buren led the Free Soil Party 's presidential ticket and appealed to many anti-slavery Democrats , possibly contributing to the victory of Whig nominee Zachary Taylor
1848 Democratic National Convention
1848 Democratic National Convention
Lewis Cass