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

"We did reach a tentative agreement," Bob Hainey, a Pepco spokesman, said Monday.

He declined to provide additional details about the pact, and a representative of the union, the International Brotherhood of Electrical Workers, could not be immediately reached for comment. The union, however, posted a note on its website that said it had made a deal with the company.

Pepco employees have been on the verge of a strike since late September when, by a 5-to-1 vote, they rejected what the utility giant described as its "last, best and final offer." The union's negotiating committee, though, described the offer as "the worst proposal this [affiliate] has faced in its entire history."

At the time of the vote, Pepco had proposed using part-time employees to staff up to 20 percent of its call center. The company, which serves about 788,000 customers in the District and Maryland, also sought to change the protocols to negotiate health benefits.

After the union beat back the proposal, workers could have taken to the picket line with as little as 48 hours notice, though negotiations continued with the assistance of a federal mediator.

Pepco, which has come under persistent criticism for its reliability, geared up for a possible strike by training members of its management team to assume the roles of union workers. The company had also been planning to use outside contractors.

Union members must still sign off on any deal before it takes effect.