SPRINGFIELD, Illinois (Reuters) - The Illinois Senate on Thursday passed a labor union-backed bill to reduce the state's nearly $100 billion unfunded public pension liability.

The 40-16 vote in the Democrat-controlled chamber sends the measure to the House, which last week passed a more comprehensive pension fix pushed by Democratic House Speaker Michael Madigan.

(Reporting By Joanne von Alroth, additional reporting by Karen Pierog in Chicago; Editing by Greg McCune)