Final answer:
Stephen Douglas's purpose in authoring the Kansas-Nebraska Act was to gain Northern support for a presidential nomination. The act applied popular sovereignty, allowing the people to decide on slavery in the territories.
Step-by-step explanation:
The purpose of Stephen Douglas in authoring the Kansas-Nebraska Act was to gain Northern support for a presidential nomination.
By proposing the act, Douglas hoped to promote economic growth and secure support from northern voters. The act applied the principle of popular sovereignty, allowing the people of the Kansas and Nebraska territories to decide whether to adopt slavery.
This act, however, resulted in violent confrontations in Kansas and further divided the nation, eventually leading to the Civil War.