Gay rights advocates said Thursday they hoped Congress will be moved to repeal the law known as "don't ask, don't tell" after a Pentagon study found it could be done with little harm to the military.

The Senate is expected to vote next month on ending the 17-year-old legislation barring gays from serving openly in the armed forces. Several senators, including Olympia Snowe, R-Maine, and Jim Webb, D-Va., have said they wanted to see the study's findings before deciding how to vote.

"These results confirm what those of us who actually know the modern military, especially the rank-and-file troops, have said all along: The men and women of America's armed forces are professionals who are capable of handling this policy change," said Alexander Nicholson, executive director of Servicemembers United.

Repeal opponents shot back, saying the group leading the study, which has not been released publicly, was biased and that selected details were leaked to the media this week in an effort to drum up public support for repeal.

"It's laughable to argue that people who anonymously leak one-sided information to a reporter are less likely to mischaracterize the findings of a 10-month study than are people who wait to read that 370-page study in full," Family Research Council President Tony Perkins said.

Defense Secretary Robert Gates ordered the review in February, calling change inevitable but saying the study was needed to prepare for an orderly transition to open gay service.

The internal assessment concluded that repeal carries little risk, with more than 70 percent of troops saying that allowing gays to serve openly would have positive, mixed or no results, according to an official familiar with the report's findings. The official spoke on condition of anonymity because the report won't be released publicly until after Dec. 1.

It long has been expected that most troops who oppose repeal are assigned to so-called combat arms duties, such as infantry.

Some officials have warned that even scattered resistance to the change could pose problems for field commanders because combat troops often are forced to live in close quarters.

According to The Washington Post, 40 percent of Marines expressed concerns about lifting the ban.

Elaine Donnelly, president of the Center for Military Readiness, said she believes opponents of repeal inside the military represent "the tip-of-the-spear troops whose views should be given heavier weight, but won't be." The group opposes lifting the ban.

Because the leaks have emphasized support rather than opposition to repeal, the Pentagon "seems to be actively trying to manage perceptions in order to distract attention from details in the report that will contradict the headline President Obama wants," she said.

Gay rights advocates called the objections raised against repeal groundless.

"No one should be surprised if a vocal minority, for a short window, might object, as a minority did when segregation in the ranks ended and women were admitted to the service academies," said Aubrey Sarvis, executive director of the Servicemembers Legal Defense Network. "In the military, you get over your objections or you get out."

Gay rights groups previously had dismissed the Pentagon study because of its methodology. Servicemembers United said this summer that the survey was "biased, derogatory and inflammatory" because it assumed troops would object to serving alongside someone who was openly gay.

Nicholson said he still believes the study was biased, but its results prove that there is little resistance to changing the law among troops.

"Had the survey been completely unbiased, it is likely that we would be seeing even higher numbers in our favor," he said.