Martin Van Buren (1782-1862) was the eighth president of the United States and a founder of the Democratic Party. A master political strategist, he was one of the most influential advisors in Andrew Jackson's administration. After serving as Jackson's Vice President, he became President himself in 1836. Yet Van Buren did not possess Jackson's military record or charisma, and his popularity suffered after the Panic of 1837. He lost to the recently-formed Whig party in 1840, which attacked him as an aristocrat and employed many of Van Buren's old tactics in their "log cabin and hard cider" campaign for war hero William Henry Harrison. Van Buren was known as "Old Kinderhook" (for Kinderhook, his hometown in New York state) and used to initial "O.K." in the margins of paperwork that received his approval. The expression soon caught on after the Boston Morning Post published it in 1839.
For most of his career, Van Buren won elections by avoiding the topic of slavery to prevent dissension between northern and southern Democrats. But in 1844, when he stood perhaps the best chance of receiving the Democratic presidential nomination for the third time, he made public his stance against the annexation of Texas because he opposed the extension of slavery and the possibility of war with Mexico. Democrats who supported annexation and western expansion prevented Van Buren from receiving the two-thirds majority and "dark horse" candidate James K. Polk became the nominee instead.