A visibly relaxed Obama spoke to several thousand enthusiastic supporters at a rally late Sunday inside a packed auditorium at Chicago State University.
He urged voters to cast their ballots early as Democrats fight to keep control of the governor's office in Illinois. Quinn is facing a stiff challenge from GOP businessman Bruce Rauner.
A poster affixed to the podium Obama spoke from reminded Illinoisans that early voting starts Monday for the Nov. 4 election.
Minutes before Obama took the stage, Quinn derided what he described as "big shots" and "high rollers." And Quinn said he stood for giving average people a "fair shake," including by raising the minimum wage.