The union representing teachers in Los Angeles has postponed the start of a planned strike from Thursday to Monday due to uncertainty over a judge would order the walkout to be delayed.

A judge was considering whether United Teachers Los Angeles (UTLA) had given legally proper notice of a strike. Union officials said they believe they would have prevailed in court but decided to postpone a strike to avoid confusion and give teachers, parents and others time to prepare.

UTLA has said its 35,000 members will walk off the job for the first time in 30 years if a deal isn't reached on higher pay and smaller class sizes. The Los Angeles Unified School District (LAUSD), the second-largest district in the nation with 640,000 students, said the delay provides an opportunity to keep talking and avoid a strike.

The Los Angeles district has offered a 6 percent raise over the first two years of a three-year contract. The union wants a 6.5 percent hike that would take effect all at once and be retroactive to fiscal 2017. Health care fully paid by the district and a pension plan would be unchanged under both proposals.

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The union also wants significantly smaller class sizes, which routinely top 30 students, and more nurses, librarians and counselors to "fully staff" the district's campuses in Los Angeles and all or parts of 31 smaller cities, plus several unincorporated areas.

The district has said the union's demands could bankrupt the school system, which is projecting a half-billion-dollar deficit this budget year and has billions obligated for pension payments and health coverage for retired teachers.

Negotiations were continuing, but little progress was evident in the contract dispute.

LAUSD Superintendent Austin Beutner traveled Wednesday to Sacramento to ask state lawmakers for additional resources for Los Angeles schools in hopes of averting a walkout.

Unlike other states, schools in California stay open if a strike happens. The Los Angeles district has hired hundreds of substitutes to replace teachers and others who leave for picket lines.

The union said it's "irresponsible" to hire substitutes and called on parents to consider keeping students home or join marchers if a strike goes forward.

Larry Sand, a retired Los Angeles and New York City teacher who heads the California Teachers Empowerment Network, said he believes the Los Angeles union sees its showdown with the district as a public "sales pitch" for organized labor now that teachers have a choice about joining after the U.S. Supreme Court ruled last year that government workers can't be required to join unions and pay dues.

Sand, whose organization describes itself as a nonpartisan information source for teachers and the public, said overly generous benefits for teachers in the past have overburdened the district.

Teachers earn between $44,000 and $86,000 a year depending on their education and experience, according to the Los Angeles County Office of Education. The district says the average teacher salary is $75,000, which reflects the older, more experienced workforce.

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The union argues that the district is hoarding reserves of $1.8 billion that could be used to fund the pay and staffing hikes. The district said that money is needed to cover retiree benefits and other expenses.

Beutner, an investment banker and former Los Angeles deputy mayor without experience in education, has become a lightning rod in negotiations.

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The union says Beutner and school board members who voted him in are trying to privatize the district, encouraging campus closures and flipping public schools into charters — privately operated public schools that compete for students and the funds they bring in.

Beutner, who attended public school, has said his plan to reorganize the district would improve services to students and families. He and his supporters on the board envision an education system with a "portfolio approach" — public and charter schools under the same leadership.

The Associated Press contributed to this report.