LOS ANGELES (AP) -- More than 50,000 Los Angeles county workers began a two-day strike Monday evening, closing libraries and disrupting administrative operations across the nation's most populous county.

The two-day strike was initiated in response to failed negotiations with the county for a new contract after the last one expired in March, according to Service Employees International Union Local 721 leaders.

The union represents more than 55,000 workers including public health professionals, social workers, parks and recreation staff, custodians, clerical workers, and more serving a county of 10 million residents. It will be the first time all of its members go on strike, the union said.

"This is the workforce that got LA County through emergency after emergency: the January wildfires, public health emergencies, mental health emergencies, social service emergencies and more," said union leader David Green in a statement. "That's why we have had it with the labor law violations and demand respect for our workers."

The strike is set to last until 7 p.m. Wednesday. During this time, libraries, some healthcare clinics, beach bathrooms, and public service counters at the Hall of Administration are expected to be closed. Some other services in the medical examiner's office and public works department may also be affected, according to the county.

The union has accused the county of 44 labor law violations during contract negotiations, including surveillance and retaliation against workers engaging in union activity and contracting out positions represented by the union.

LA County says it's facing "unprecedented stresses" on its budget, including a tentative $4 billion settlement of thousands of childhood sexual assault claims, a projected $2 billion in impacts related to the LA wildfires in January, and the potential loss of hundreds of millions in federal funding.

"We do not want to negotiate ourselves into a structural deficit--which could lead to layoffs and service reductions," spokesperson Elizabeth Marcellino said in a statement from the chief executive office. "We are trying to strike a balance: fair compensation for our workforce while sustaining services and avoiding layoffs in the midst of some of the worst financial challenges we have ever experienced."

The city of LA is facing similar financial woes -- Mayor Karen Bass's recently proposed budget includes 1,600 layoffs of city workers amid a nearly $1 billion deficit.