Abraham Lincoln and Stephen Douglas first met in 1834, as rising first-term representatives in the Illinois General Assembly. The two men were twenty-four and twenty-one, respectively. From the first, they had been healthy rivals, each pulling a considerable amount of weight within his own party. Additionally, Douglas had briefly courted Mary Todd before Lincoln won her hand.
Although three years Lincoln's junior, Douglas enjoyed a quicker ascent to national prominence. As Lincoln's last term in the state legislature expired, Douglas earned an appointment to the state supreme court. When Lincoln was elected to Congress in 1846, Douglas enjoyed a promotion to senator in the bargain. By the early 1850s, Douglas enjoyed a reputation as one of the sharpest young orators and politicians in the Senate.
From the beginning, Douglas's position slavery stood in stark contrast to Lincoln's. Whereas Lincoln was wont to style slavery as a moral evil, Douglas was somewhat indifferent as to the morality of slavery, and far more concerned with the politics of the issue that was beginning to tear the nation apart at the seams.
Henry Clay, in his inimitable way, had once again stepped in to save the union with his Compromise of 1850, which provided for the admission of California as a free state, the organization of the New Mexico and Utah territories without mention of slavery, the abolishment of the slave trade in the District of Columbia, and, most significantly, a powerful federal fugitive slave law designed to restore runaway slaves back to their masters. Lincoln, always a great admirer of Clay, personally approved of the Compromise of 1850. Two years later, upon Clay's death, Lincoln would praise him for his compassionate moderate politics in a public eulogy.
Therefore, it must have been especially galling to Lincoln when Douglas effectively nullified Clay's Missouri Compromise with the passage of his controversial Kansas-Nebraska Act of 1854. In this piece of legislation, the original line dividing free states from slave states was ignored, since each territory seeking entry into the union was empowered to decide the question of slavery for themselves under the system of popular sovereignty.
Douglas was primarily motivated to advance the doctrine of popular sovereignty in order to garner support for quite another project. Plans for the transcontinental railroad were being laid out, and there was some debate as to whether the eastern terminus of the track should be at Chicago or New Orleans. Wishing to improve the lot of his home state, and recognizing the necessity of the railroad to the industrial growth of the middle west, Douglas threw the Kansas-Nebraska Act into the ring in hopes that he could earn southern votes for his Chicago campaign. In the short term, this proved to be a brilliant political move for Douglas, as he succeeded in securing the railroad for the north and won the approval and support of the south in one fell swoop. However, in the longer view, Douglas's politicking would prove to be his own undoing, and indeed, the undoing of the union.