Following a survey of U.S. troops and their families, a Pentagon study group has concluded the military can lift the ban on gays serving openly in uniform with only minimal and isolated incidents of risk to the current war efforts, The Washington Post reported Wednesday.

The newspaper quoted two people familiar with a draft of the study, which is to be completed for Defense Secretary Robert Gates by Dec. 1., but with an uncertain public release date.

More than 70 percent of respondents to a survey sent to active-duty and reserve troops over the summer said the effect of repealing the military's "don't ask, don't tell" policy on gays and lesbians in uniform would be positive, mixed or nonexistent, the sources told the newspaper.

The newspaper said the survey results have led the report's authors to conclude that objections to openly gay colleagues would drop once troops were able to live and serve alongside them.

The long, detailed and nuanced report will almost certainly be used by opponents and supporters of repeal legislation to bolster their positions in what is likely to be a heated and partisan congressional debate. And it is expected to reveal challenges the services could face in overturning the long-held policy, including overcoming fierce opposition in some parts of the force — primarily in the Army and Marine Corps — even if they represent a minority.

The Marine Corps commandant, Gen. James Amos, last week said that with forces fighting in Afghanistan and still deployed in Iraq, now was the wrong time to lift the ban.

"This is not a social thing. This is combat effectiveness," Amos said.

That brought a mild rebuke from Joint Chiefs of Staff Chairman Mike Mullen, who said he was surprised that Amos had spoken publicly. He said the heads of the military services had committed to "look at the data and then make our recommendations privately."

The Post said Gates, Mullen and uniformed and civilian leaders of the four military branches received copies of the draft report late last week.

The document totaled about 370 pages and is divided into two sections, the newspaper said. The first section explores whether repealing "don't ask, don't tell" would harm unit readiness or morale. The second part of the report presents a plan for ending enforcement of the ban. It is not meant to serve as the military's official instruction manual on the issue but could be used if military leaders agreed, one of the sources told the newspaper.

Among other questions, the survey asked whether having an openly gay person in a unit would have an effect in an intense combat situation. Although a majority of respondents signaled no strong objections, a significant minority is opposed to serving alongside openly gay troops. About 40 percent of the Marine Corps is concerned about lifting the ban, according to one of the people familiar with the report, the Post said.

Pentagon spokeswoman Cynthia Smith said that of the 400,000 surveys sent randomly to troops, 115,052 responded. An additional 150,000 surveys were sent to spouses with 44,266 completed. Defense officials have said they were pleased with the response rate and believed it was enough to get an accurate sampling of the force.

President Barack Obama has vowed to end the policy. A Democratic proposal to repeal the 1993 law already has passed the House as part of a broader defense policy bill that includes such popular provisions as a pay raise for the troops. But that same legislation sank in the Senate under Republican objections just weeks before the Nov. 2 elections.

Senate Majority Leader Harry Reid, D-Nev., has promised another vote by year's end, although the political dynamics in this lame-duck session haven't changed much. Gates has asked Congress to act before January, but Senate Democrats still hold a shaky majority and they are unlikely to give into Republican demands for a protracted debate.

A Republican gay rights group, the Log Cabin Republicans, has challenged the constitutionality of the policy in court. The Obama administration on Wednesday urged the Supreme Court to keep the "don't ask, don't tell" policy in place while a federal appeals court considers the issue.

The administration filed court papers in defense of an appeals court order that allowed "don't ask, don't tell" to go back into effect after a federal judge declared it unconstitutional and barred its enforcement. The 9th U.S. Circuit Court of Appeals in San Francisco is reviewing the administration's appeal.

The Log Cabin Republicans asked the Supreme Court to step into the case to reverse the appeals court decision that has allowed "don't ask, don't tell" to remain in effect despite the order by U.S. District Judge Virginia Phillips.

Among several recommendations, the Pentagon report urges an end to the military ban on sodomy between consenting adults regardless of what Congress or the federal courts might do about "don't ask, don't tell," the source told the Post.

The report also concludes that gay troops should not be put into a special class for equal employment or discrimination purposes, that person said. The recommendation is based on feedback the study group obtained from gay troops and same-sex partners who said they do not want a special classification, according to the source.

The report recommends few, if any, changes to policy covering military housing and benefits because the military must abide by the federal Defense of Marriage Act, which does not recognize same-sex marriage.