GRAND RAPIDS, Mich. -  Substitute teachers will be asked to fill in if Grand Rapids Public Schools teachers walk off the job, but union representatives have asked them to stay away, according to The Grand Rapids Press.

Grand Rapids school leaders said they will try to keep schools open if teachers fail to show up for classes, The Press reported, relying on substitutes hired through the Professional Education Services Group, a private firm which provides substitute teachers for most of the county.

Union members have been contacting substitutes through letters and phone calls, asking them not to get involved, The Press reported, but the district's human services department sent a letter to PESG employees saying that, "You should not be threatened or coerced to forsake opportunities for employment."

The most recent contract expired more than a year ago.

The Grand Rapids Press, "Substitute teachers pulled further into rift between Grand Rapids administrators, teachers," Oct. 23, 2008

Michigan Education Digest, "Grand Rapids contract still unresolved," Sept. 23, 2008