[119] He argued the decision was at variance with the Declaration of Independence; he said that while the founding fathers did not believe all men equal in every respect, they believed all men were equal "in certain inalienable rights, among which are life, liberty, and the pursuit of happiness".[120]

Lincoln–Douglas debates and Cooper Union speech
Further information: Lincoln–Douglas debates and Cooper Union speech
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.[121] Some eastern Republicans supported Douglas for his opposition to the Lecompton Constitution and admission of Kansas as a slave state.[122] 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.[123]

Abraham Lincoln, a portrait by Mathew Brady taken February 27, 1860, the day of Lincoln's Cooper Union speech
Lincoln accepted the nomination with great enthusiasm and zeal. 