OAKLAND (CBS SF) — Negotiators for the city of Oakland and the larger of two striking unions have agreed to try to settle the strike in mediation starting Monday, the two sides said Saturday night.

The strike is in its fifth day. City leaders said they expect the strike to continue Sunday, Monday and “until further notice.”

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“This continued strike is harming our most vulnerable residents,” Oakland Mayor Libby Schaaf said in a statement.

Schaaf said, “We will continue to work with SEIU in good faith, and remain responsible and fair to ‘both’ our workers as well as our residents. We cannot spend money we do not have, particularly as we know our pension costs are escalating at least 49 percent over the next five years.”

Chris Flink, spokesman for the Service Employees International Union Local 1021, said, “On Monday we’ll see if the city’s negotiators are willing to work with the mediator and the striking workers to reach an agreement. The unfair labor practice strike continues.”

SEIU Local 1021 represents more than 2,000 of the 3,000 workers on strike since Tuesday.

City employees are also represented by the International Federation of Professional and Technical Engineers Local 21.

Oakland leaders declared an impasse in the negotiations Friday but later in the day Schaaf said that if the workers didn’t accept the city’s final offer, she hoped they would agree to enter mediation.

Hours later, Rob Szykowny, chief negotiator for SEIU Local 1021, announced that workers had contacted the city to identify a mediator.

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The mayor said the unions rejected the city’s final offer early Friday morning and made a counter-offer that she claimed is “too financially risky” for the city to accept.

Schaaf said the unions have already had an 8 percent raise over the previous two years and the city is offering a 4 percent wage increase retroactive to July 1 and a possible 2 percent wage increase in June 2019, depending on growth in city revenue.

But Flink said the strike is not over wages.

According to the union, the strike is to protest unfair labor practices by the city, workplace conditions, understaffing levels and cost of living concerns.

Flink said the strike was prompted by a complaint union officials filed after workers were intimidated and retaliated against following a partial-day strike in November.

SEIU Local 1021 represents public works employees, parking enforcement officers, Head Start instructors and early education teachers.

IFPTE Local 21 represents about 1,000 professional and technical employees, including engineers, building inspectors and planners.

Union employees held a large rally in front of City Hall during the lunch hour Friday. At the rally, several local and state elected officials offered their support to the employees and urged the city to meet their demands.

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The city’s contract talks with the unions are now in their seventh month and Schaaf said the city has been meeting with them an average of four times a week in an effort to reach an agreement.