Pepco has reached a tentative, four-year labor deal with workers who were threatening to strike, though the agreement still faces a vote by a union that resoundingly rejected an offer from the power company just weeks ago.

"After extended negotiations over the weekend, Pepco and [the union] have reached a tentative agreement," said Pepco spokeswoman Myra Oppel, who declined to provide details of the pact.

Jim Griffin, president of the International Brotherhood of Electrical Workers Local 1900, also refused to discuss the agreement's terms on Monday, but he said he was supportive of the plan.

"The union will be recommending that the membership accept the offer," Griffin said. A vote will likely take place late next week.

Approximately 1,150 Pepco employees have been on the verge of a strike since September, when they rejected by a 5-1 margin what the utility giant described as its "last, best and final offer."

Union leaders, however, described the plan as "the worst proposal this local has faced in its entire history."

In that proposal, Pepco, which serves about 788,000 customers in the District and Maryland, sought to make changes to its call center staffing and the protocols for negotiating employees' health benefits.

After the union beat back that plan, workers could have taken to the picket line within 48 hours, though negotiations continued with the assistance of a federal mediator.

Pepco, a target of persistent criticism over its reliability of service, geared up for a possible strike by training its management team to assume the roles of union workers. The company had also been planning to hire outside contractors.

The accord was a victory for Pepco -- named the nation's "most hated company" in 2011 by Business Insider -- as it moved closer to ending the specter of a work stoppage that threatened to unleash customer frustrations anew.

The company has endured repeated tests this year, including a powerful June storm that knocked out electricity to thousands of customers for days during a triple-digit heat wave.

The company has also faced pushback on its efforts to raise rates. D.C. and Maryland regulators alike refused to support raising rates as much as Pepco sought, though the company received approvals for small increases.