WASHINGTON — The country’s top military leaders offered split testimony before the Senate Armed Services Committee on Friday about scrapping “Don’t Ask Don’t Tell,” the policy that prevents gays from openly serving in the armed forces.

Friday’s hearings was the second of two consecutive days of testimony, which follow a new Pentagon study that recommended repeal of the 17-year-old policy.

U.S. Sen. Susan Collins, R-Maine, serves on the Senate Armed Services Committee. (Editor’s Note: This story was updated at 1:15 p.m. to reflect that Sen. Collins did attend a portion of today’s hearing.)

Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff; Adm. Gary Roughead, chief of naval operations; and Admiral Robert Papp, commandant of the U.S. Coast Guard, all said they supported the study’s recommendation for repeal.

But Gen. James Amos, commandant of the U.S. Marine Corps; Gen. George Casey, Jr., U.S. Army chief of staff; and Gen. Norton Schwartz, U.S. Air Force chief of staff, disagreed. They doubted the study’s conclusion that the short-term risk to military effectiveness would be low.

Although the policy could be effectively repealed, they added, doing so while combat forces were deployed was unwise.

“I believe that implementation of the repeal of DADT in the near term will add another level of stress to an already stretched force, be more difficult in combat arms units and be more difficult for the army that the report suggests,” Casey said. “That said, if repeal is directed, the implementation principles in the report constitute a sold basis upon which to develop implementation plans that will help mitigate the risks I just described.”

Collins was the only Republican committee member to support repealing the policy when it was first considered by the committee.

U.S. Sen. Olympia Snowe, R-Maine, said Thursday she was monitoring the hearing and continuing to review the Pentagon report, but had concerns about supporting repeal.

“Particularly, the question right now, being that we are at war; I was noticing some of the high percentages in the combat units that had concerns (about repeal),” she said in an interview.

Maine’s Republican senators have been targeted by groups pushing for repeal. Maine veterans and the Maine Civil Liberties Union staged a press conference Thursday in Portland to press them to support repeal; pop star Lady Gaga also made a trip to Maine in September before a scheduled Senate vote on the issue.

That vote failed, but another vote on the policy — which is included as an amendment in the defense budget authorization legislation — could come during Congress’ lame-duck session.

“I don’t know how it will come up here,” Snowe said. “They haven’t said and they haven’t indicated that at this point, what’s on the agenda.”

The U.S. House of Representatives voted to repeal DADT in May. U.S. Reps. Chellie Pingree, D-1st District, and Mike Michaud, D-2nd District, both supported that measure.