Senator Stephen A. Douglas proclaimed the doctrine of territorial or "popular" sovereignty—which asserted that the settlers in a territory had the same rights as states in the Union to establish or disestablish slavery as a purely local matter. The Kansas–Nebraska Act of 1854 legislated this doctrine. In the Kansas Territory, years of pro and anti-slavery violence and political conflict erupted; the congressional House of Representatives voted to admit Kansas as a free state in early 1860, but its admission did not pass the Senate until January 1861, after the departure of Southern senators.