Who was selected in 1844 as a dark horse or little-known candidate?

In 1844, James K. Polk was selected as the dark horse candidate for the Democratic Party. He was relatively unknown compared to other prominent figures in the party, such as Martin Van Buren. Polk's campaign focused on expansionism, particularly the annexation of Texas and the Oregon Territory, which resonated with voters and ultimately led to his election as the 11th President of the United States.