The CTA has contended that under state law, essential service employees can't strike, and that includes bus drivers. The drivers' contract with the CTA contains a clause that any issue that can't be resolved by negotiation must go to binding arbitration.

Jefferson said the "essential services" prohibition does not apply to bus drivers.

The CTA hasn't said exactly what it wants from the unions yet, but Jefferson said he has heard from management sources that the agency wants union workers to forgo 3.5 percent raises scheduled for 2010 and 2011. Jefferson said the agency should instead cut more managers.