WASHINGTON -- The chairman of the Joint Chiefs of Staff said Sunday he supports a repeal of the military's "don't ask, don't tell" policy but he would like Congress to wait on a vote until after the Pentagon completes its review about the impact of allowing gay troops to serve openly.

Adm. Mike Mullen told "Fox News Sunday" that the military brass is working hard to "understand what's going on with our troops," and so he would like the legislation to wait until the review is complete. But he acknowledged he has no control over Congress' actions. 

"I don't manage the legislative calendar," he said, adding that it could "be many more months before this legislation is passed."

A House voted Friday to repeal the ban. But the vote also gives the Pentagon until year's end to study how to make that happen. A Senate committee approved the change Thursday, but the full Senate isn't expected to act for months.

Mullen said he doesn't want to inject the military forces into the middle of the debate because he doesn't want to "electrify this force in the middle of two wars, for the length of time we've been at war."

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A senior defense official on Friday said troops with concerns about the repeal are less willing to speak freely because the vote makes the outcome clear. The official, who is knowledgeable about the troop consultations, spoke on condition of anonymity because he was not authorized to discuss the Pentagon response.

Some troops feel double-crossed, the official said, because they had been told that nothing would happen quickly and were assured that the Pentagon would take their individual concerns into account. These misgivings about the political process have been aired over the past week at town-hall style events where troops are encouraged to share any doubts about repeal, the official said.

Sen. Jim Webb said he was disturbed that the Senate Armed Services Committee, of which he is a member, voted on Thursday to repeal the ban. The full Senate is not expected to act for months. The Virginia Democrat echoed Mullen's concern about not allowing members of the military to express their views before Congress acted.

"I believe we had a process in place and to pre-empt it in some ways showed a disrespect for the people in the military," Webb said on CNN.

Colin Powell, the retired Army general who opposed allowing gays to serve openly when he was chairman of the Joint Chiefs of Staff and the 1993 law was enacted, said he now supports repeal and believes it will happen. Powell noted on ABC's "This Week" that he voiced one of a unanimous opinion 17 years ago.

"The president said we're going to do it. It's a decision," Powell said. "And the Congress has to pass the law to allow that. And so let's take the time to make the study, see what the implications are."

Obama has vowed to help repeal the 1993 law, which prohibits the military from asking service members whether they are gay, but bans homosexual activity and requires that gay troops not discuss their sexual orientation.