The possibility of a strike by New York City's school bus drivers inched closer on Sunday, with the schools chancellor, Dennis M. Walcott, detailing contingency plans for the 152,000 public and private students who could be affected, as, steps away, hundreds of bus drivers, union leaders and parents noisily protested the loss of job security in new contracts.
The City Education Department said that a strike could begin this week and that it wanted to warn parents.
"They're playing our children in an unfortunate way as far as making them not know what will be happening with school," Mr. Walcott said at a midday news conference at the department's headquarters, at the Tweed Courthouse in Lower Manhattan.
But at a rally outside City Hall, just south of the old courthouse, Michael Cordiello, the president of Local 1181 of the Amalgamated Transit Union, representing 9,000 bus drivers, urged the city to negotiate, saying a strike would be "the last card we want to play."
At issue was the department's announcement last month that it would be accepting competitive bids for 1,100 of its routes -- about a sixth of the total -- for children with disabilities. Though the other routes are not affected and some bus companies are nonunion, the department said any job action could spread.
Drivers, union leaders and many parents object to the lack of job security measures, known as employee protection provisions, in the new contracts, and said broader issues, like safety and the competence of drivers and onboard matrons, were at stake.
"I stand with them. These jobs need to have respectable wages," said Carin van der Donk, who, with her husband, the actor Vincent D'Onofrio, has a son with disabilities and is an advocate for improving bus transportation. "They need more training, not less."
Mr. Walcott insisted that drivers hired under new contracts would receive proper training and accused the union of preying on parents' fears.
The department hopes to drive down busing costs, which it says hover around $1.1 billion a year, or $6,900 per child, the highest in the country. By comparison, according to Mr. Walcott, the cost in Los Angeles is $3,124 per student.
Money saved by the new contracts would, he said, be devoted to classroom needs.
Among the backup plans the department is making are these: children who take yellow buses could receive MetroCards through their schools; parents of younger children could be given MetroCards; and those whose schools were inaccessible by public transportation could be reimbursed for mileage or cabs.
School bus drivers last went on strike in 1979; the 13-week walkout ended after the protections were put in place.
Until the summer of 2011, the Bloomberg administration argued in a lawsuit brought by nonunion bus companies that the job protections, which require companies to hire drivers and other employees based on seniority, should be preserved. The city even drafted a bill in Albany that would have enshrined the protections in law. Mr. Walcott said a ruling that year by the State Court of Appeals legally prohibited the city from including the protections in new contracts. But a lawyer for the union said the decision applied only to contracts for prekindergarten students.
Mr. Cordiello said the union was not opposed to competitive bidding, as long as the protections remained.
Dwight Daniels, 60, of the Bronx, who has been a driver for 35 years and remembers the strike, said he could not imagine being able to keep his job without the protection provision. "It's impossible to live as it is," he said.
This article originally appeared in The New York Times.