In a 57-40 vote, the Senate failed to get the 60 votes needed on a key procedural move to start debate on overturning the "Don't Ask, Don't Tell" policy.

The vote went largely along party lines.

Reversing the 1993 policy now looks unlikely to happen any time soon, although supporters vowed to try again before year's end.

In a statement, Manchin said he wanted to "make clear that my concern is not with the idea of repealing DADT, but rather an issue of timing."

"While I believe the "Don't Ask, Don't Tell" (DADT) policy will be repealed someday, and probably should be repealed in the near future, I do not support its repeal at this time," he said in the statement.

"I truly understand that my position will anger those who believe repeal should happen now, and for that I sincerely apologize," Manchin said. "While I am very sympathetic to those who passionately support the repeal, as a senator of just three weeks, I have not had the opportunity to visit and hear the full range of viewpoints from the citizens of West Virginia."

Sen. Jay Rockefeller, also D-W.Va., voted to advance the repeal.

"Sen. Rockefeller believes this is fundamentally a military decision," spokeswoman Rebecca Gale said. "Our military leaders, after receiving extensive input at all levels, have asked for authority to chart a new course with the 'Don't Ask, Don't Tell' policy, and Sen. Rockefeller has voted to support them."

President Obama urged senators to reconsider the issue by the end of the year, saying he was "extremely disappointed" in Thursday's vote. The provision to repeal DADT was attached to a defense-spending bill.

"Despite having the bipartisan support of a clear majority of senators, a minority of senators are standing in the way of the funding upon which our troops, veterans and military families depend," Obama said.

 A Pentagon survey released last week said that about two-thirds of the military did not think repealing the ban would harm their units, although doing so could cause short-term disruptions.

Fairness West Virginia, a statewide group that advocates for gays and lesbians, said Manchin's vote was a huge let-down.

"This goes beyond disappointment," group president Stephen Skinner said. "We don't understand why Senator Manchin didn't trust [the late Sen. Robert C. Byrd] on his decision to vote for the repeal. Keeping this policy in place makes us less safe and threatens security every single day."

In May, the U.S. House of Representatives voted to overturn the ban. At that time, Byrd announced he would support a repeal in the U.S. Senate. He died in June.

"Personally, I think that once [Manchin] looks at the leadership and the rest of the Democratic Party, and moderate Republicans, he'll understand that his position is far from the mainstream," Skinner said.

The Family Policy Council of West Virginia praised Manchin's vote.

"We are grateful that Sen. Manchin has not allowed religious liberty, free speech and national security to take a back seat to the homosexual agenda in this country," Council President Jeremy Dys said.

The Associated Press contributed to this report. Reach Alison Knezevich at alis...@wvgazette.com or 304-348-1240.