Van Buren easily won renomination for a second term at the 1840 Democratic National Convention , but he and his party faced a difficult election in 1840 . Van Buren 's term had been a difficult affair , with the U.S. economy mired in a severe downturn , and other divisive issues , such as slavery , western expansion , and tensions with Great Britain provided numerous for opportunities for Van Buren 's political opponents to criticize his actions . Although Van Buren 's renomination was never in doubt , Democratic strategists began to question the wisdom of keeping Johnson on the ticket . Even former president Jackson conceded that Johnson was a liability and insisted on former House Speaker James K. Polk of Tennessee as Van Buren 's new running mate . Van Buren was reluctant to drop Johnson , who was popular with workers and radicals in the North and added military experience to the ticket , which might prove important if the Whigs nominated William Henry Harrison . Rather than re-nominating Johnson , the Democratic convention decided to allow state Democratic Party leaders to select the vice-presidential candidates for their states
1840 Democratic National Convention
1840 Democratic National Convention
Presidency of Martin Van Buren