Democratic US Senator Stephen A. Douglas , an author of the Nebraska-Kansas Act who was seeking the 1856 Democratic presidential nomination and who would be up for reelection as a senator in two years , sought to bolster his electoral prospects by utilizing the Chicago mayoral election to illustrate popular support in Illinois for his stance on slavery ( he was a prominent supporter of applying the principle of popular sovereignty to slavery ) . Douglas strongly backed Dyer and sought to frame the mayoral race as a referendum about his stance on slavery . He and his allies had much to gain by making this the key issue of the election
1856 Democratic presidential nomination
1856 Democratic National Convention
1856 Chicago mayoral election