Answer:
1. Illinois
2. Stephen A. Douglas and Abraham Lincoln
3. Issue of Slavery Extension
Step-by-step explanation:
Towards the Senatorial Election, both Stephen A. Douglas, a Democrats candidate and Abraham Lincoln, a Republican candidate, went into series of debates, focusing on the Issue of Slavery Extension into the new Western states.
Following the aftermath of Mexican war, some states were added to the United States, which includes California, Nevada, Utah etc.
Therfore, in the bid to seek the public favour, both the Senatorial aspirants, entered series of debates to argue the Issue of Slavery Extension in the new Western States.
While, Stephen A. Douglas proposed that the issue of Slavery should be left to the states to determine how to deal with it, Abraham Lincoln offered a different opinion.
In the end, the debates took places in Ottawa, Freeport, Galesburg, Quincy, Charleston, Jonesboro and Alton.
Hence, In 1859 the two candidates for US sentor from ILLINOIS were STEPHEN A. DOUGLASand ABRAHAM LINCOLN . In their campaign debates they argued about THE ISSUE OF SLAVERY EXTENSION in the new western states.