WASHINGTON — House lawmakers on Wednesday again approved a bill to repeal the “don’t ask, don’t tell” law, delivering renewed momentum to the years-long campaign to end the ban on gays serving openly in the military before a possible Senate vote next week.

The House voted 250-175 to repeal the 17-year-old law; 15 Republicans voted for the bill, and 15 Democrats voted against it.

The 75-vote margin was wider than in a House vote in May, when language to end the ban was part of the annual defense authorization bill. That bill failed in a procedural vote in the Senate last week, requiring another vote in the House on a separate measure to end the ban.

President Obama heralded the vote, saying in a written statement that ending current military policy “is not only the right thing to do, it will also give our military the clarity and certainty it deserves. We must ensure that Americans who are willing to risk their lives for their country are treated fairly and equally by their country.”

Democratic Rep. Chellie Pingree of Maine spoke Wednesday on the floor of the House, urging her colleagues to repeal “don’t ask, don’t tell.”

“There are no more excuses not to repeal this misguided and harmful policy. There is no reason to delay this any longer,” she said.

Pingree cited a recent Pentagon study in which the vast majority of military personnel said that allowing openly gay men and women to serve would have no adverse effect on the readiness of their units.

“How many more hearings and how much more testimony are we going to ask for, before we finally hear what the men and women of the armed services have said: Just because someone is gay doesn’t make them any less of a soldier, sailor, airman or Marine,” she said.

Democratic Rep. Mike Michaud of Maine also voted to repeal the policy.

The Senate will not vote on the bill before next week, said a spokeswoman for Senate Majority Leader Harry Reid, D-Nev.

The bill’s Senate sponsors, Joseph Lieberman, I-Conn., and Susan Collins, R-Maine, called for a quick vote. “We are out of excuses,” they said Wednesday in a written statement.

Efforts to end “don’t ask, don’t tell” picked up a significant backer Wednesday in Sen. Olympia Snowe, R-Maine. She said she would vote to repeal the law, joining Collins and Sens. Scott Brown of Massachusetts and Lisa Murkowski of Alaska as Republicans who have said they would do so — enough, when combined with the 57 Democrats who supported last week’s failed attempt, to overcome any attempt at a filibuster.

Snowe said in a prepared statement, “After careful analysis of the comprehensive report compiled by the Department of Defense and thorough consideration of the testimony provided by the Secretary of Defense, the Chairman of the Joint Chiefs of Staff and the service chiefs, I support repeal of the ‘don’t ask, don’t tell’ law.”

Snowe has voted twice — in September and last week — against advancing the defense spending bill that included the repeal, saying she opposed ending debate because Republicans had not been given time to air concerns or offer amendments.

She also had resisted weighing in on repeal pending a military review of the policy, which was released Nov. 30.

In her statement, Snowe conditioned her support on lawmakers voting to continue funding the government and passing a tax cut compromise first. She said it was “misguided judgment” to include repeal of the policy in the defense authorization bill.

“We could have avoided this situation, where three weeks before the end of the legislative session we are without a national defense authorization bill for the first time in 48 years,” she said. “The Senate should have considered — and passed — this critical $725 billion defense authorization bill in the spring, and then taken up ‘don’t ask, don’t tell’ on its own merits after the Defense Department’s review was scheduled to be released.”

Collins, a member of the Senate Armed Services Committee, was the only Republican lawmaker to support repeal when the original measure was passed out of committee in May. She voted against moving the defense bill forward in September, but voted in support last week.

Though Lieberman and Collins introduced the bill first, its House co-sponsors, Majority Leader Steny Hoyer, D-Md., and Rep. Patrick Murphy, D-Pa., pushed their colleagues to vote first so the Senate could consider it later as a privileged resolution, which requires fewer days of debate.

“It’s time to end a policy of official discrimination that has cost America the service of some 13,500 men and women who wore our uniform with honor,” Hoyer said Wednesday. “It’s time to stop throwing away their service — their willingness to die for our country — because of who they are.”

“The ball is now in the Senate’s court, and I urge our senators of both parties to pass this bill and finally dismantle ‘don’t ask, don’t tell’ once and for all,” Murphy said.

Rep. Buck McKeon, R-Calif., who is scheduled to chair the House Armed Services Committee in the next Congress, criticized Democrats for calling for a vote on “don’t ask, don’t tell” before reconsidering the defense authorization bill. “That’s a bad system,” he said.

House and Senate negotiators completed negotiations Wednesday on a new version of the defense bill that does not include provisions dealing with “don’t ask, don’t tell.” Senate Armed Services Committee Chairman Carl Levin, D-Mich., and the panel’s ranking member, John McCain, R-Ariz., called on Congress to pass the bill before the lame-duck session ends.

In a joint statement, gay-rights groups pushing to end the ban cheered Wednesday’s vote, saying it “provides another resounding indication that ‘don’t ask, don’t tell’ can and should be repealed legislatively this year.”

The groups, ranging from the liberal think tank Center for American Progress to the Log Cabin Republicans, plan to spend the rest of the week lobbying moderate Republican senators, including Richard Lugar of Indiana and George Voinovich of Ohio. Neither has said in recent days how they might vote.

Defense Secretary Robert Gates also asked the Senate on Wednesday to quickly pass the bill. Doing so would enable the Defense Department “to carefully and responsibly manage a change in this policy, instead of risking an abrupt change resulting from a decision in the courts,” said Pentagon spokesman Geoff Morrell.

A majority of Americans support allowing gays and lesbians to serve openly in uniform, according to a Washington Post-ABC News poll released this week.

Staff Writer Dennis Hoey and MaineToday Media State House Writer Rebekah Metzler contributed to this report.