Chicago Mayor Rahm Emanuel on Thursday defended the Chicago Transit Authority’s plan to close its budget deficit largely through union contract negotiations.

The CTA is proposing changes to union work rules that it says would save the agency $160 million to avoid fare increases and service cuts. Those savings, however, are contingent on union leaders agreeing to the proposed reforms. Emanuel says it’s time for the unions to concede some of their contract benefits.

“In the past the commuter paid, just two years ago, higher rates,” said Emanuel. “In the past, the commuter, just a year ago, paid in service cuts. It’s time for everyone else to contribute to strengthening the system.”

CTA says an agreement must be reached by July 1 of next year to avoid more fare hikes, service cuts or layoffs.

Meanwhile, union leaders have called the proposed budget union busting.