Manifest Destiny was the belief that American settlers were destined to expand across North America, which triggered the sectional crisis by intensifying debates over the expansion of slavery into new territories. In his speech against the Compromise of 1850, Calhoun argued that the South's position was that slavery should be allowed to expand, and the crisis could only be solved by accepting slavery in all territories. During the Lincoln-Douglas debates, Republicans viewed African Americans as equal to whites and opposed the expansion of slavery, while Northern Democrats accepted the inequality of the races and were open to the spread of slavery.