WASHINGTON — An internal Pentagon study has found that most U.S. troops and their families don't care whether gays are allowed to serve openly and think the policy of "don't ask, don't tell" could be done away with, according to officials familiar with its findings.

The survey results were expected to be used by gay rights advocates to bolster their argument that the 1993 law on gays could be repealed immediately with little harm done to the military. But the survey also was expected to reveal challenges the services could face in overturning the long-held policy, including overcoming fierce opposition in some parts of the military even if they represent a minority.

Details on the survey results were still scarce Thursday, with the Pentagon declining to discuss the findings until after Dec. 1 when it rolls out its own plan for repeal.

The officials who disclosed the survey's findings spoke on condition of anonymity because the results had not been released.

NBC News' Richard Engel first reported the findings Thursday, and appeared that evening on "The Rachel Maddow Show."

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President Barack Obama has said "don't ask, don't tell" unfairly discriminates against gays. Defense Secretary Robert Gates and Adm. Mike Mullen, the military's top uniformed officer, agree but want to move slowly to ensure that military effectiveness doesn't suffer.

Among their top concerns is that forcing too much change, too soon on an institution that historically has been reluctant to embrace gays could prompt a backlash among troops and their families.

With a Democratic-controlled Congress already considering a change to the law, Gates in February ordered a yearlong study into the matter. As part of that effort, the Pentagon sent out some 400,000 surveys to troops and another 150,000 to family members on the military's policy toward gays.

Officials said that with the survey results complete, the working group is analyzing the results and working on a plan to overturn the policy should Congress repeal the law.

Gay rights groups attacked the 103-question survey. They said it assumes troops don't want to serve with openly gay service members and repeatedly uses the term "homosexual," considered to be outdated and derogatory.

The survey was prepared by the Maryland-based research firm Westat under a $4.5 million contract.

Earlier this month, the Pentagon was forced to lift its ban on openly serving gays for eight days after a federal judge in California ordered the military to do so. The Justice Department has appealed and a federal appeals court granted a temporary stay of the injunction.