Clinton, Military at Impasse on Gay Ban : Defense: Homosexual activists initiate lobbying effort aimed at White House. Key obstacle is Pentagon’s insistence on service incompatibility.

Just two weeks before President Clinton is scheduled to decide whether and how to lift a ban on homosexuals in the military, he and top Pentagon officials are said to be at an impasse that has stymied efforts to resolve the issue ahead of schedule--and perhaps at all.

At the same time, gay activists--sensing their last, best hope for change in Clinton--have begun a flurry of quiet campaigning directed at the White House.

Gay activist and Clinton friend David Mixner met with White House aides several times this week to try to convince them that the President could prevail over a congressional challenge should he decisively lift the ban.

A chief cause of the impasse is the Pentagon’s determination to retain in the new policy a declaration that homosexuality is “incompatible with military service”--a statement that gay activists consider unacceptable and Clinton finds distasteful.

Beyond that, the White House and the Pentagon appear to remain divided over whether gay service personnel could discuss their homosexuality privately with colleagues without jeopardizing their careers.

Those subjects and others were discussed for more than two hours Friday by Defense Secretary Les Aspin and the Joint Chiefs of Staff, who met to draft a final proposal to be relayed to the White House. Senior defense officials and participants in the private talks refused to discuss any conclusions produced at the meeting.

But Marine Corps Commandant Carl E. Mundy Jr., who has participated in all other major sessions on the issue, said Thursday he is confident that the Pentagon’s final recommendation would allow homosexuals to serve in the military, as long as they do not reveal their sexual preference--a position that the President has opposed.

Knowledgeable officials at the Pentagon said the service chiefs have been holding out for strict limits on the rights of service members to declare their homosexuality, off-duty as well as on. In addition, several of the chiefs have resisted any change in the current Defense Department guidelines, which state that homosexuality is incompatible with military service.

If a proposal goes to the White House with those provisions in it, the President will be in a difficult bind. He has been eager to win the full backing of the chiefs for his proposal and may need it if he is to thwart attempts by lawmakers to block his efforts. Republican supporters of the ban have warned that if Clinton attempts to lift it, they would try to write it into law.

Officials close to the President said he would find it difficult to accept both the “incompatibility” language and harsh restrictions on the rights of service members to confide their sexual orientation to friends and colleagues.

Moreover, gay and lesbian activists have warned the White House that their reaction would be swift and angry if Clinton agrees to such strictures to win the chiefs’ backing. They also argue it may not be necessary for him to compromise.

A spokesman for a gay and lesbian lobbying group said that his organization has been buoyed by recent figures indicating Clinton could win in a face-off with Congress over the issue.

According to a head count by the organization, the Campaign for Military Service, a vote on the ban in Congress would be close. Furthermore, the group maintains, the White House could win if Clinton were to fight hard enough. But it remains unclear how much political capital the President would be willing to expend in such a fight.