Stephen Douglas was a challenging opponent for Abraham Lincoln when the two were running for election to the Senate for the state of Illinois in 1858. Douglas chose the politically expedient route, advocating throughout the series of debates that popular sovereignty was the only way to settle the issue; let the people of a new territory decide, he said, whether or not slavery would be allowed. Douglas took issue with Lincoln's declaration that "A house divided against itself cannot stand." While Lincoln insisted that the nation would not be able to function indefinitely as half-slave/half-free, Douglas argued that it (the United States) had always existed that way, and would continue in perpetuity if the people of a territory could simply be left to their own devices.
Lincoln, for his part, acknowledged that he did not believe blacks equal to whites, but that he did believe the system of slavery was fundamentally at odds with the ideals of the United States Constitution in particular, and democracy in general. In conjunction with this focus on the ideals of the nation, Lincoln did not hesitate to mention as a matter of course that Douglas's authorship of the Kansas-Nebraska Act had overturned the Missouri Compromise of 1820, and didn't it appear that perhaps Douglas's primary agenda was to keep the slaveowning coalition happy?
While Douglas may have won the battle, so to speak, Lincoln won the war. Douglas was elected to the Senate in 1858; however, when next the two men met on the political field, in the presidential election of Lincoln had the clear advantage. His remarks in the 1858 campaign had earned him a reputation as a reasonable moderate, and his focus on higher democratic ideals gave him a staying power that Douglas's short term solution simply could not offer. In short, Lincoln seemed to have a vision for a great nation, while Douglas seemed to many to have had only a vision for getting elected.