The school bus workers’ union has threatened to strike as early as next week in a move that would throw more than 152,000 public school students and their families into chaos, city officials warned today.

The strike threat stems from the union’s bid to secure from the city what amounts to lifetime job guarantees for roughly 500 drivers and escorts who work on pre-kindergarten routes — even though the state’s highest court has ruled those protections unlawful.

“We are deeply concerned about the impact of a strike on our students and families,” Schools Chancellor Dennis Walcott wrote in a letter to parents outlining the city’s contingency plans.

These include providing $1.3 million in Metrocards per day to students who currently get yellow bus service, and reimbursing parents for shuttling their special needs kids to and from school.

Yellow bus service costs the city about $5 million per day, or nearly $1 billion annually.

Walcott and Mayor Bloomberg both called the potential strike “illegal” and said the city was seeking an injunction in federal court to prevent it.

Amalgamated Transit Union officials said a strike was “likely” but emphasized that there were no immediate plans for one.

The contracts at the heart of the dust-up cover less than 10 percent of kids who ride yellow buses.

The job protections the union is seeking would require any bus company that wins a pre-k contract with the city in 2012-13 to fill open positions with the most senior workers who get cut from companies that lose routes.

Local 1181 president Michael Cordiello argued that not preserving an experienced workforce and hiring drivers on the cheap “directly threatens the safety and security of our children.”

But the State Court of Appeals ruled in June that those protections have “anti-competitive and cost-inflating effects” and barred the city from including them in its pre-k contracts.

Surprisingly, the city had supported the job protections until then on the grounds that maintaining veteran drivers would yield better service. They also worried that excluding the provisions would lead to a strike.

When the city tried to insert the driver protections into pre-k special education busing contracts in 2008, busing companies filed the lawsuit out of fear that the measure would jack up their labor costs.

Those same job protections have been included in busing contracts that service older children since 1979, after school bus drivers went on strike for three months.

Critics say the protections have led the same bus companies to get contracts with the city for decades, raised costs, and fostered a corruption-friendly environment.

Information about any disruptions to yellow bus service will be posted to http://schools.nyc.gov.

(Source: NY Post)