Doug Mills/The New York Times

In his State of the Union address in January, President Obama repeated a campaign-trail promise to the gay community.

By the end of the year, Mr. Obama said, he would seek a full repeal of the military’s “don’t ask, don’t tell” policy.

The president called it a “law that denies gay Americans the right to serve the country they love because of who they are,” and he said repealing it was “the right thing to do.”

The promise faces a critical test today as supporters of the current policy say they will try to filibuster military defense legislation that includes the repeal. With midterm elections just six weeks away, a unified Republicans filibuster would likely mean a delay in fulfilling the president’s pledge until next year.

Opponents of an unrelated immigration measure included in the annual defense authorization bill are also vowing to filibuster, increasing the odds that both issues will be put off.

If the Democrats can’t muster 60 votes to cut off debate, the delay on “don’t ask, don’t tell” would be a blow to gay activists, members of a key White House constituency who fear that next year’s Congress will be less sympathetic to a repeal of the 17-year-old ban. The policy was enacted during President Bill Clinton’s first term.

And it would serve as another source of frustration for those who do not think Mr. Obama is moving quickly enough to make good on major promises, including a repeal of the Defense of Marriage Act and passage of legislation to ban discrimination against gays in hiring.

“It’s critical that it get done in the next week or so,” Aubrey Sarvis, the executive director of the Servicemembers Legal Defense Network, said of the repeal of the military policy.



The network and other groups have praised Mr. Obama and his White House for helping to negotiate a deal with Democratic lawmakers that moved a repeal effort forward while allowing the Pentagon to conduct a study on how best to implement the change in policy. That led to public announcements of support for the repeal in May by Defense Secretary Robert M. Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff.

But Mr. Sarvis said on Monday: “We need the administration to weigh in and ask the Senate to take up this bill. I haven’t heard the president’s voice in recent days on this issue. But I know he’s an advocate for repeal. He wants repeal.”

Repeal is one of a series of promises that Mr. Obama made in the early days of his administration, only to find that negotiations with Congress were more difficult than he had imagined. The president’s pledge to close the military prison at Guantánamo Bay, Cuba, also remains unfulfilled, with little sign that a solution will come soon.

Among the biggest critics of the “don’t ask, don’t tell” repeal has been Senator John McCain, Republican of Arizona, a longtime member of the Senate Armed Services committee. Mr. McCain has said consideration of such an idea in Congress should wait until the Pentagon’s study is completed.

As today’s vote neared, advocates for repeal stepped up their lobbying. They paid particular attention to the two moderate Republican senators from Maine, Olympia J. Snowe and Susan Collins. Ms. Collins voted on the Armed Services committee to support the repeal, but both senators have expressed concern about the defense spending bill, largely on procedural grounds.

In a statement on Monday, Ms. Snowe said that the Democratic leadership should allow Republicans to offer amendments to the defense bill.

Craig Dilger for The New York Times

“The Senate should have the ability to debate more than the three amendments the majority leader is allowing, especially as this bill is the largest discretionary authorization measure that Congress considers,” Ms. Snowe said in the statement.

The pop music sensation Lady Gaga traveled to Maine on Monday evening for a rally in support of the repeal. “If you are not honorable enough to fight without prejudice, go home,” she told the crowd at the rally.

The immigration provision in the defense spending bill would provide a path to citizenship for young people who have lived in the United States for five years and spent two years in either college or the military.

A White House spokesman, Shin Inouye, declined to comment on the “don’t ask, don’t tell” or the immigration provisions, but said Monday night that the spending bill was “important for the overall health and well being of our forces, especially given the ongoing campaigns in Iraq, Afghanistan, and around the world.”

“This legislation received bipartisan support in the House and in the Senate Armed Services Committee, and the president hopes it receives similar bipartisan support in the Senate,” Mr. Inouye said.

Two senators, Richard Durbin, Democrat of Illinois, and Joseph I. Lieberman, a Connecticut independent, plan to hold a news conference this morning to urge their colleagues to vote in favor of moving the legislation forward.

The vote is scheduled for around 2:15 this afternoon.