Final answer:
Stephen Douglas won the 1858 Senate election in Illinois, defeating Abraham Lincoln despite the famous debates that raised Lincoln's national profile.
Step-by-step explanation:
In the 1858 Senate election in Illinois, the Republican candidate Abraham Lincoln challenged the incumbent Democrat Stephen Douglas. Despite a series of high-profile debates between Lincoln and Douglas, which garnered national attention, and Lincoln's rising prominence as an anti-slavery Republican, it was Stephen Douglas who ultimately won the election and retained his seat in the Senate. The election is famous for the Lincoln-Douglas debates which highlighted the central issue of slavery and helped to elevate Lincoln's status, setting the stage for his eventual presidential run in 1860.