Cass and Douglas hoped they could finesse the question of support for or opposition to slavery. Douglas applied "popular sovereignty" to Kansas in the Kansas-Nebraska Act, which passed Congress in 1854. The Act stated that in Kansas and Nebraska, "every free white male inhabitant above the age of twenty-one years...shall be entitled to vote at the first election".

The Act had two unexpected results. By dropping the Missouri Compromise of 1820 under which said slavery would never be allowed