While Illinois, the home of President Barack Obama, has been reliably Democratic in recent years, Republicans say long-running fiscal stress and the nation’s lowest credit rating grant them a good shot at the governor’s office. Labor leaders are keen to reverse regional momentum against them, which they say is propelled by billionaires Charles and David Koch, brothers who have bankrolled conservative causes and candidates, including Walker.

“Illinois is part of the pattern — these rich folks are going wherever they see an opportunity, just like they did in Wisconsin, Indiana and Michigan,” said Henry Bayer, executive director of the American Federation of State County and Municipal Employees Council 31, representing 95,000 workers and retirees in the state. “Illinois is experiencing some real difficulties, so they think they can make some inroads.”

Illinois is fertile ground for discontent. In December, it had the nation’s third-highest unemployment rate, 8.6 percent. It has the worst-funded state pensions and its stack of unpaid bills adds up to about $5 billion. The governors preceding Quinn, Democrat Rod Blagojevich and Republican George Ryan, were convicted on corruption charges and sentenced to prison.

“This could be a state that could swing,” said Pat Brady, former chairman of the Illinois Republican Party.