WASHINGTON (Reuters) - A wary U.S. military prepared on Tuesday for an eventual repeal of its “don’t ask, don’t tell” policy barring gays from serving openly, but made clear movement should be gradual on the politically charged change requested by President Barack Obama.

The Pentagon will take at least a year to act.

Obama called for repeal of “don’t ask, don’t tell” in his State of the Union address last week, putting a spotlight on the hot-button issue before congressional elections in November and in the middle of efforts to get his budget through a skeptical Congress.

Many gay activists were frustrated last year that Obama had not moved quickly to carry out a promise to overturn “don’t ask, don’t tell.” Gays and lesbians strongly backed Obama during his 2008 presidential campaign.

Defense Secretary Robert Gates, who has voiced caution in the past against moving too quickly to repeal the policy, said he fully supported Obama’s decision and announced a team of advisers to start reviewing steps the U.S. military would have to take to integrate openly gay servicemembers.

“The question before us is not whether the military prepares to make this change, but how we best prepare for it,” Gates told the Senate Armed Services Committee. “We received our orders from the commander in chief and we are moving out accordingly.”

Americans favor allowing gays to serve openly in the military by a margin of 56 percent to 37 percent, according to an April poll of just over 2,000 registered voters by Quinnipiac University. Support was higher among younger voters, although there was majority support in every age group.

Many top military officers and Republicans in Congress assert that having gays openly serve in uniform would undermine morale and discipline.

“At this moment of immense hardship for our armed services, we should not be seeking to overturn the ‘don’t ask, don’t tell policy,” said Republican Senator John McCain, who was his party’s presidential nominee and lost the 2008 election to Obama, a Democrat.

Defense Secretary Robert Gates and Chairman of the Joint Chiefs of Staff Navy Admiral Michael Mullen depart a news conference at the Pentagon, February 1, 2010. REUTERS/Jonathan Ernst

The internal Pentagon review, to be led by Army General Carter Ham and General Counsel Jeh Johnson, is expected to look at sensitive issues including how a change might affect unit cohesion, recruitment and retention, as well as the possibility of extending marriage and bereavement benefits to the partners of gay soldiers.

REVIEW BY END OF 2010

Gates said the review team would complete an implementation plan by the end of 2010, but that additional time would be needed to carry out the panel’s recommendations.

As an interim step, Gates said, the Pentagon would review existing policies within 45 days to determine how “don’t ask, don’t tell” could be enforced in a more “humane and fair manner.” This could include halting disciplinary proceedings against gay members of the military who are “outed” by others.

Opponents of “don’t ask, don’t tell” say the policy is ineffective and unfair.

“Speaking for myself and myself only, it is my personal and professional belief that allowing homosexuals to serve openly would be the right thing to do,” the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, told the Senate panel.

“I have served with homosexuals since 1968,” Mullen added. “Everybody in the military has.”

The “don’t ask, don’t tell” policy was signed into law in 1993 by Democratic President Bill Clinton as a compromise after the military objected to his calls to open its doors to gays.

It bans openly gay people from serving in the military but prohibits military officials from initiating inquiries on sexual orientation when soldiers are abiding by the rules.

More than 13,500 members of the military have been dismissed under the law, according to the Servicemembers Legal Defense Network, an advocacy group that opposes the ban.