Obama called for repeal of the 1993 "don't ask, don't tell" law near the end of his State of the Union speech, addressing the issue in a single, passing mention, but rekindling the debate between supporters and opponents of the move.
During his presidential campaign, Obama promised to end "don't ask don't tell," but has not pushed the issue as president, to the disappointment of supporters, including gays and lesbians.
Some saw his mention of the issue Wednesday as a reminder to an important constituency that he remains on their side. But the lack of a specific plan or instructions to the military left supporters of repeal discouraged.
"We wish we had heard him speak of concrete steps tonight," said Rea Carey, director of the National Gay and Lesbian Task Force. "The next time the president speaks about our community, we expect him to provide a concrete blueprint."
Opponents of letting gays openly serve criticized Obama for the stand.
"At a time when our armed forces are fighting and sacrificing on the battlefield, now is not the time to abandon the policy," said Sen. John McCain (R.-Ariz.), who was Obama's presidential opponent in 2008.
Republicans pledged to block any legislative push for repeal. But Democrats, citing polls that show up to 69% of voters support allowing gays to serve in the military, have urged White House to push to change the law.
"We look forward to working with him on this issue of fundamental fairness and supporting the patriotic Americans who serve and wish to serve our country in uniform," said House Speaker Nancy Pelosi (D-Calif.) in a statement.
Pentagon Press Secretary Geoff Morrell said Wednesday that Defense Secretary Robert M. Gates would elaborate on the administration's plans in the coming days.
Within the military, there have been signals that the services would be more receptive to a shift than they were in 1993. Articles in military publications have cast doubt on the argument that "unit cohesion" would suffer if gays were allowed to serve openly.
Gates and Admiral Michael G. Mullen, the chairman of the Joint Chiefs of Staff, have begun work to examine how to implement a change in the law. They have told military audiences to expect a change in the policy.
If gays are allowed to serve openly, Defense officials are considering measures to limit public displays of affection on military bases and addressing such potential problems as port calls in nations that outlaw homosexuality.
Some critics called Obama's comment pandering to the left.
"Civilian activists do not understand or respect the culture of the military," said Elaine Donnelly, president of the Center for Military Readiness, a think tank that opposes allowing gays in the military. "I'm sure the troops will be disheartened by this."
Some supporters of repealing "don't ask, don't tell" saw Obama's comments as a sign of possible progress in coming months.
"Repealing 'don't ask, don't tell' is a bold move by the president, but one that is desperately needed to enhance our military readiness for our troops in combat," said Jon Soltz, chairman of VoteVets, which supports allowing gays to serve openly.
Janet Hook in Washington contributed to this report.