LOS ANGELES (Reuters) - More than 30,000 teachers were expected to walk off the job in public schools across Los Angeles on Monday, staging their first strike in three decades after union leaders said they were “insulted” by the latest contract offer from district officials.

Barring an unlikely 11th-hour deal between United Teachers Los Angeles and the nation’s second-largest school district, students arriving early on Monday for classes at some 900 campuses will be met by picketing teachers, who also plan a boisterous rally and march to City Hall.

“This is our moment. This is our movement. Solidarity is pouring in, from Los Angeles to London, from Palms to Puerto Rico. Tomorrow. The dedication & passion educators bring every day to the classroom, will be brought to the streets to demand the #schoolsourstudentsdeserve!,” UTLA said in a tweet on Sunday.

The union wants a 6.5 percent pay raise, more librarians, counselors and nurses on campuses, smaller class sizes and less testing, as well as a moratorium on new charter schools.

Negotiators for the Los Angeles County School District, which educates some 600,000 students, have countered with a proposed 6 percent salary hike with back pay and a $100 million investment to hire more staff and decrease class size.

Schools Superintendent Austin Beutner said Friday’s latest offer to teachers was beefed up after newly installed California Governor Gavin Newsom increased education spending in his proposed budget for the coming fiscal year.

Union bargaining chair Arlene Inouye said she and her fellow negotiators were “insulted” by the proposal. The two sides have not met since Friday.

The union had called for the strike last week, but postponed it until Monday after the district said it had not been given a legally required 10-day notice of the labor action.

The district has urged teachers not to walk out, saying it would hurt the more than 600,000 students who returned from winter break only last week as well as their mostly working-class parents, who would struggle to provide childcare.

“A strike will harm the students, families and communities we serve, and we have a responsibility to resolve the situation without a strike,” the district said after negotiations stalled on Friday.

A strike in Los Angeles would mark the latest job action by teachers nationwide who have called for better pay and working conditions.

Educators in Oakland, California, staged a rally on Saturday in support of their colleagues across the state, while teachers in Denver have said they will walk out on Monday as well if a deal is not reached on a new contract.