Legislators returned to Springfield on Monday to finish the session that ends Sunday.
At the center of their fight is how to erase a roughly $6 billion deficit in next year's budget.
Democrats want a tax increase to close some of that gap. Rauner and other GOP lawmakers say they're open to raising taxes, but only if the Legislature passes pro-business legislation that Rauner wants.
Several other measures could get caught in the legislative gridlock. They include a plan to expand gambling and a new capital construction program to repair crumbling roads and bridges.