Stephen Arnold Douglas was an American politician and lawyer from Illinois. He was one of two Democratic Party nominees for president in the 1860 presidential election, which was won by Republican Abraham Lincoln. Douglas had previously defeated Lincoln in the 1858 United States Senate election in Illinois, known for the Lincoln–Douglas debates. During the 1850s, Douglas was one of the foremost advocates of popular sovereignty, which held that each territory should be allowed to determine whether to permit slavery within its borders. Douglas was nicknamed the "Little Giant" because he was short in physical stature but a forceful and dominant figure in politics.
Born in Brandon, Vermont, Douglas migrated to Jacksonville, Illinois, in 1833 to establish a legal practice. He experienced early success in politics as a member of the Democratic Party, serving in the Illinois House of Representatives and various other positions. He resigned from the Supreme Court of Illinois upon being elected to the United States House of Representatives in 1843. Douglas became an ally of President James K. Polk, and favored the annexation of Texas and the Mexican–American War.