At first blush, Illinois seems like a lock for an incumbent Democratic governor.

The population leans left. Democrats control most of state government, and this year's race is likely to turn on the Chicago area, one of the few places President Barack Obama can still bring large crowds to their feet.

But Democratic Gov. Pat Quinn is battling to survive against Bruce Rauner, a wealthy businessman Republicans are banking on to exploit the state's deep economic problems and reputation for cronyism.

Quinn is an often-folksy Chicago Democrat who has held his own despite the state's many crises.

Rauner has sunk more than $25 million into his own campaign. He's blasted Quinn over Illinois' massive budget problems and a plan to make a temporary income tax increase permanent.