New York City officials say they expect to save hundreds of millions of dollars by putting school bus routes that serve 135,000 children out to bid.

The move to bid out the contracts for 4,100 bus routes Tuesday comes after a monthlong strike earlier this year over job protections in school bus contracts.

Mayor Michael Bloomberg said Monday that putting the contracts out to bid means more money goes into the classroom.

But the Amalgamated Transit Union says that hundreds of bus drivers whose jobs were protected under the old contracts have been laid off.

The union has said that Mayor-elect Bill de Blasio could cancel the new contracts.

A spokeswoman for de Blasio said it would be premature to comment.

(AP)