More than 150,000 New York City public school students could be taking public transit to school for the first time if the local school bus union follows through on a plan to strike immediately.

Amalgamated Transit Union Local 1181, which represents the city's yellow school bus drivers, informed the city earlier this week that all its school bus drivers will strike if the city does not bend to its demands for new worker protections, according to Mayor Michael Bloomberg and city Schools Chancellor Dennis Walcott.

The union's threat to strike and leave 152,000 students and their families in a lurch is nothing short of shameful, Wallcott said Friday. We still hope for the best but unfortunately the school bus union has left us with no option but to prepare for the worst.

The union told the city Thursday that it will go on strike if the city does not insert an Employee Protection Provision into its pre-K school bus driver contract bid for next year, something Bloomberg said a state Appeals Court judge has ruled illegal for the city to provide.

The city put out a bid without the provision Friday, so Bloomberg and Walcott responded to the threats during a noon press conference at City Hall.

Bloomberg and Walcott stated that the city has requested that the federal National Labor Relations Board seek an injunction against the union in federal court as soon as possible.

The union representing school bus drivers is offering something we cannot legally offer - job guarantees for certain current drivers, Bloomberg said. We know this is a very difficult situation for all of us and that it may be very upsetting for our students and our families.

If the union follows through on its promise and strikes, the Metropolitan Transit Authority will provide the city with hundreds of thousands of MetroCards, which students will be able to use to take transit to school and back each day for free. Parents of young and special-needs children will also be given the two-trip passes if they request them.

Messages left at the union's headquarters and the offices of two school bus companies in Queens and Staten Island were not immediately returned Friday afternoon.

The city will post any information about disruptions to bus service at schools.nyc.gov