Leaders of Washington's labor unions voted last night to endorse Hilda H.M. Mason's bid to retain her at-large D.C. Council seat, but decided against endorsing Democratic nominee Linda W. Cropp, Mayor Marion Barry or any other candidate for the second at-large seat.

Barry, who is running as an independent for one of two at-large seats in the city's Nov. 6 elections, promptly hailed the action by the Metropolitan Washington Council of the AFL-CIO as a political victory, saying he had worked hard to ensure that Cropp did not win the labor group's endorsement.

"I called all my friends," Barry said. "They did all right."

Cropp disputed that, saying the labor vote "represents a defeat for the mayor because it indicates he no longer enjoys the support of organized labor."

Mason, a Statehood Party leader running for her fourth term on the 13-member council, won the labor endorsement on a unanimous vote, union officials said.

Barry, the three-term mayor, and Cropp, a member of the D.C. Board of Education, were nominated for endorsements during the labor council's hour-long meeting, but neither mustered the needed two-thirds vote, union leaders said.

The labor council, the umbrella group for 175 union locals representing 75,000 D.C. residents, has traditionally been an important organizing base for citywide candidates.

The council had been scheduled to make an endorsement in the mayoral contest between Democrat Sharon Pratt Dixon and Republican Maurice T. Turner Jr., but delayed its vote because Dixon had the flu.

Joslyn N. Williams, the labor group's president, who also is the head of the city Democrats, said the unions endorsed only Mason because of a widely held view that the 74-year-old council member "has the greatest chance of losing."

As for Cropp, whose party has long been allied with organized labor, "there was a belief that we should not willy-nilly endorse a candidate just because they're the nominee of the Democratic Party," Williams added.

Five candidates are running for two at-large seats in the November election, and the top two vote-getters will capture those seats. In addition to Barry, Cropp and Mason, other candidates are W. Cardell Shelton, the Republican nominee, and Ray Browne and Clarene Martin, both independents.

At-large hopeful Jim Harvey, who was ruled ineligible as a candidate after some of his petition signatures were challenged, said yesterday he intends to go to court next week in an effort to get on the ballot.

Williams, an occasional critic of Barry's, said that although the labor council vote reflected some of the mayor's political strength, Barry could take little solace in Cropp's failure to win an endorsement.

"If he construes this as a victory, it's a rather hollow victory," Williams said.

Blondell Stewart-Ware, the president of a Communication Workers local, said she was glad that Cropp did not triumph over her favorite candidate, Barry. "The mayor still has considerable support among labor people," Stewart-Ware said.