WASHINGTON - A proposal to step up the repeal of the ban on gays and lesbians serving openly in the military but still allow the Pentagon time - perhaps even years - to implement new policies won the White House's backing on Monday after administration officials met with gay rights activists.

The White House budget office sent a letter supporting the proposal to remove the Clinton-era "don't ask, don't tell" law even as the Pentagon continues a review of the system. Implementation of policy for gays serving openly would still require the approval of President Barack Obama, Defense Secretary Robert Gates and the chairman of the Joint Chiefs of Staff, Adm. Mike Mullen. How long implementation might take is not known, but the proposed amendment would have no effect on current practices.

"The proposed amendment will allow for completion of the comprehensive review, enable the Department of Defense to assess the results of the review, and ensure that the implementation of the of the repeal is consistent with standards of military readiness, effectiveness, unit cohesion, recruiting and retention," budget chief Peter Orszag wrote in identical evening letters to Pennsylvania Rep. Patrick Murphy, Connecticut Sen. Joe Lieberman and Michigan Sen. Carl Levin - the Democrats leading the push for repeal

Murphy, an Iraq war veteran, was expected to introduce the legislative proposal on Tuesday. Gay rights groups urged a quick vote, which could come as early as Thursday.

"Without a repeal vote by Congress this year, the Pentagon's hands are tied and the armed forces will be forced to continue adhering to the discriminatory 'don't ask, don't tell' law," said Joe Solmonese, president of the Human Rights Campaign.

The White House had hoped lawmakers would delay action until Pentagon officials had completed their study so fellow Democrats would not face criticism that they moved too quickly or too far ahead of public opinion in this election year. Instead, administration officials recognized it could not stop Congress in its effort to repeal the 1993 ban and joined the negotiations.

Hours after activists met at the White House, top Democratic lawmakers met on Capitol Hill and approved the final version of a brokered deal that adds the repeal to the annual defense spending bill.

Obama called for the repeal during his State of the Union address this year, and Gates and Mullen have echoed his views but have cautioned any action must be paced.

In a speech last year at the Army War College in Carlisle, Pa., Gates noted that the 1948 executive order for racial integration took five years to implement.

"I'm not saying that's a model for this, but I'm saying that I believe this is something that needs to be done very, very carefully," he told the audience.

One organization dedicated to repealing the law urged supporters to hold celebration.

"President Obama's support and Secretary Gates' buy-in should ensure a winning vote, but we are not there yet," said Aubrey Sarvis, an Army veteran and Servicemembers Legal Defense Network executive director. "The votes still need to be worked and counted."

The administration has argued that any repeal should start in Congress and have the backing of top military leaders. Gay rights activists criticized the administration as Obama did little to push for a repeal during his first year in office.

On Capitol Hill, the third-ranking House Republican promised unified GOP opposition to lifting the ban. "The American people don't want the American military to be used to advance a liberal political agenda. And House Republicans will stand on that principle," said Mike Pence, R-Ind.

Pence urged Democrats who control both chambers to wait until the Pentagon completes its review of what a repeal would take.

Congress led hearings on a repeal and heard testimony from Gates and Mullen - the top uniformed official in the country - in favor of repeal. Additionally, a Gallup poll earlier this month found 70 percent of American favor allowing gays and lesbians to serve openly.

Obama's relationship with gay activists has been rocky since his election. Gays and lesbians objected to the invitation of evangelist Rev. Rick Warren's to participate in Obama's inauguration because of Warren's support for repealing gay marriage in California. Obama responded by having Episcopalian Bishop V. Gene Robinson, the denomination's first openly gay bishop, participate at another event.

Obama has taken a slow and incremental approach to the politically charged issues. He has expanded some federal benefits to same-sex partners, but not health benefits or pension guarantees. He has allowed State Department employees to include their same-sex partners in certain embassy programs already available to opposite-sex spouses.

The military's "don't ask, don't tell" policy was imposed by a 1993 law intended as a compromise between President Bill Clinton, who wanted to lift the ban on gays entirely, and a reluctant Congress and military that said doing so would threaten order.

Under the policy, the military can't ask recruits their sexual orientation. In turn, service members can't say they are gay or bisexual, engage in homosexual activity or marry a member of the same sex.

Between 1997 and 2008, the Defense Department discharged more than 10,500 service members for violating the policy.

Associated Press writers Anne Flaherty and Jim Abrams contributed to this report.