They were in 2 different sides. The Abolitionists and the Pro-Slavery politicians. Some were heavily against slavery and started a movement to abolish it, some even tried freeing slaves. Pro-slavery politicians were in heavy support of it and did everything in their power to keep it alive in the South. It got to the point where all the Southern States threatened to secede from the United States in the late 1850s, and even caused Virginia to split into 2 states, Virginia and West Virginia.
