At the time, U.S. senators were elected by state legislatures; thus Lincoln and Douglas were trying for their respective parties to win control of the Illinois legislature. The debates previewed the issues that Lincoln would face in the aftermath of his victory in the 1860 presidential election.lthough Illinois, itself, was a free state, the main issue discussed in all seven debates was slavery in the United States. In agreeing to the debates, Lincoln and Douglas decided to hold one debate in each of the nine congressional districts in Illinois.