Members of Yale’s two largest unions, who say they made little progress this summer in contract negotiations with the University, plan to stop work and go on strike Aug. 27, the day the University opens its housing to students.

Representatives for locals 34 and 35, who held a five-day strike in March but failed to accomplish any significant goals at the bargaining table, wrote in a letter last week to Yale Health Services administrators that workers will begin a walkout at 5 a.m. Union leaders, who will be joined in the walkout by unionized workers at Yale-New Haven Hospital, did not say how long the strike will last.

Some members of the Graduate Employees and Students Organization, which also joined in the March job action, will support unions on picket lines this fall but will not stop teaching.

The announcement comes as Yale and locals 34 and 35, which represent nearly 4,000 clerical, technical, service and maintenance workers, enter their 19th month since the beginning of contract negotiations. Talks have faltered since last summer, as the two sides have clashed over wages, benefits and other noneconomic issues.

Local 34 President Laura Smith said union leaders still hope the three bargaining sessions scheduled for this week will be productive.

“We’re doing everything we possibly can to settle this without a strike,” she said. “But we’re not ready to settle for less than we deserve and less than Yale deserves.”

During the strike, union members will not work in dining halls, perform administrative duties, clean buildings or any other work in Yale facilities. Striking workers will form picket lines around central campus buildings, leaders said. The Rev. Jesse Jackson and other prominent social activists will also come to campus to speak to striking union members.

Workers will receive a picket pay of about $150 each week they are on strike, Smith said.

Yale spokesman Tom Conroy said the University is trying to ensure that the strike will be minimally disruptive. He said students, parents and faculty members will receive letters detailing the University’s contingency plan later this week.

“[We] will do whatever is necessary to ensure that the school year begins as planned,” he said.

Conroy said the University has an attractive offer on the table.

“The University is offering to provide a better contract in every aspect,” he said. “It’s clear that the University has done all that one could reasonably expect to reach a contract without a strike.”

The two sides did not hold any bargaining sessions for most of the summer but resumed negotiations Aug. 12. The following day, Yale presented an offer that would have tripled the bonus each worker receives for signing the contract from $500 to $1,500.

University negotiators also proposed an increase in second-year wages for members of both unions, from four to five percent for Local 34 and three to 3.5 percent for Local 35. In addition, Yale’s proposal would have adjusted the multiplier that is used to determine the value of workers’ pensions from 1.05 to 1.1 percent for earnings over $20,000.

The unions made a counter-offer, lowering their pension multiplier proposal from 2.1 percent to 1.95 percent.

The unions will also present a new contract offer on Thursday at the Omni Hotel.

The planned strike would be the ninth job action in the last 11 rounds of contract talks. It would also be the first time unions held two strikes over the same contract proposal, union representatives said.

Leaders on both sides have disputed the effectiveness of the March walkout. Union leaders said they had a high rate of member participation during the strike. But Yale officials have said they believe union members’ response to the March job action was unenthusiastic.

The two sides have also disagreed over the reasons for the prolonged contract dispute. While union representatives have said Yale’s offer is financially inadequate, University leaders have said in the past that the organizing drives of GESO and 1,800 hospital workers have prevented a contract settlement.

GESO has been trying to organize graduate students for over a decade, but Yale administrators have consistently maintained that graduate students are not employees and cannot organize.

GESO chairwoman Anita Seth GRD ’05 said because most GESO members are not yet back in town, the organization has not been able to decide whether to hold a strike. She said members will picket alongside union members and will urge students and faculty members not to cross picket lines.

The Service Employees International Union District 1199, which represents 160 dietary workers at the hospital, is currently in the process of negotiating a new contract for the dietary workers and is also trying to organize other hospital workers. Yale officials have said they do not have control over the hospital because it is a separate institution.

District 1199 is closely aligned with locals 34 and 35.

Hospital spokeswoman Katie Krauss said she does not think the strike will significantly disrupt hospital operations. During the March walkout, she said, managers and professional staff volunteered their time to take over the work of those on strike.

“We do not anticipate any problems in maintaining food service,” Krauss said.

Yale and union negotiators will continue to meet at the bargaining table through Thursday of this week. No sessions are scheduled for next week, leaders said.