Stephen A. Douglas (1813-1861) was an Illinois politician who dominated the U.S. Senate throughout the 1850s. He is perhaps best remembered for engaging in a series of fiery debates with Republican Abraham Lincoln during the 1858 Illinois senatorial race. Douglas ultimately defeated Lincoln in the race for that Senate seat, but it was Lincoln who gained the most from the contest. Two years later, boosted by his reputation as a brilliant orator, Lincoln handily defeated Douglas in the presidential race.
In 1854, Illinois Senator Stephen Douglas sponsored the Kansas-Nebraska Act. The act allowed settlers in newly organized territories north of Missouri to decide amongst themselves whether slavery would be allowed. By reopening the bitterly contentious question of slavery in the territories, Douglas's actions led to the repeal of the Missouri Compromise of 1820, heightening political tensions and leading directly to the creation of the antislavery Republican Party.