Douglas was up for re-election in the U.S. Senate

In 1858 Douglas was up for re-election in the U.S. Senate, and Lincoln hoped to defeat him. Many in the party felt that a former Whig should be nominated in 1858, and Lincoln's 1856 campaigning and support of Trumbull had earned him a favor. Some eastern Republicans supported Douglas from his opposition to the Lecompton Constitution and admission of Kansas as a slave state. Many Illinois Republicans resented this eastern interference. For the first time, Illinois Republicans held a convention to agree upon a Senate candidate, and Lincoln won the nomination with little opposition.