The Fraternal Order of Police won a landslide victory yesterday over two other unions challenging it to become the bargaining agent for rank-and-file D.C. police officers.

The FOP, the incumbent union, received more than 86 percent of the 2,328 eligible votes cast and immediately declared a "mandate" from its membership to continue to press for a pay raise in the current round of negotiations with the city.

"We're ecstatic," said Gary Hankins, chairman of the FOP's labor committee.

"We're going to redouble our efforts to be worthy of this kind of mandate," he added.

Officials said the FOP won 2,011 of the 2,390 votes cast, compared with 247 for the National Association of Government Employees/International Brotherhood of Police Officers and 63 for the American Federation of Government Employees (AFL-CIO). Officials said 62 votes were disallowed and 7 ballots were marked "no union."

Voting, which was conducted by mail, was described as heavy. Officials said ballots were sent to 3,574 eligible officers. About 67 percent returned their ballots to the American Arbitration Association, where they were opened and counted yesterday.

In soundly turning aside the challenge by the other two unions -- the IBPO received about 11 percent of the votes and the AFGE received less than 3 percent -- officers seemed to be firmly behind the FOP in its efforts to win concessions from the city at the bargaining table.

"We asked our membership to make this a referendum on our record and on our bargaining," Hankins said. "The only thing this election would do is tell everyone, including us, whether our members stood behind us."

In an interview last week, Donald H. Weinberg, head of the D.C. Office of Labor Relations, said the city was further away from signing a contract with the FOP than with any other union.

"They haven't even gotten to the economics yet," Weinberg said. "They're still dealing with the working conditions."

In addition, Weinberg said, the FOP is one of three city-employe bargaining agents that has not agreed to the pay proposal offered by Mayor Marion Barry in the current round of negotiations. The proposal offers city workers a one-time bonus of 3 percent of their salary or $500, whichever is greater, instead of a pay increase, which would boost their base wages.

"I think the main thing it the FOP victory does for us is provide continuity with the unit we've been bargaining with," Weinberg said yesterday.

The election was significant also because there no longer is a possibility that D.C. police and corrections officers will be represented by the same union, which city officials said could have led to a conflict of interest if guards ever went on strike and police officers were called in to replace them.

Last summer, more than half of the corrections officers, who are represented by the AFGE, signed a petition for an election to allow them to choose the FOP as their bargaining agent. In inconclusive balloting Tuesday, the FOP placed third among three unions vying to represent corrections officers. Because neither of the top two unions -- the AFGE and the International Brotherhood of Teamsters -- received a majority, they will have a majority runoff election. The FOP dropped out of the contest.