Opponents of overturning the military’s “don’t ask, don’t tell” policy are cranking up their rhetoric and threatening roadblocks on multiple fronts, including what promises to be a fierce Senate floor fight, as the tide appears to be turning against them.

Supporters of overturning the policy appear poised to score a major victory today in the Senate Armed Services Committee, where they likely have the votes to attach repeal language to the defense authorization bill.

That could help sway adoption of the same language on the House floor perhaps as soon as today as part of that chamber’s consideration of the defense bill.

Attuned to the momentum repeal backers are gaining, opponents have upped the ante.

Senate Armed Services ranking member John McCain said Thursday that he would “without a doubt” support a filibuster if the bill goes to the floor with language that Sen. Joe Lieberman (ID-Conn.) plans to offer as an amendment during today’s markup.

“I’ll do everything in my power,” the Arizona Republican said, citing letters from the four service chiefs urging Congress not to act before a Pentagon review of the policy is complete. “I’m going to do everything I can to support the men and women of the military and to fight what is clearly a political agenda.”

Another Armed Services Republican, Sen. Roger Wicker, also said he would support a filibuster if the repeal language makes it into the version of the bill that goes to the floor, possibly during the post-Memorial Day work period.

“If it is adopted, I will not sign the conference report, and there will be an attempt to filibuster the bill on the floor,” the Mississippi Republican said. “It’s a major mistake.”

Wicker described repeal as “a huge shift,” adding: “This bill is not the place for social policy. … Why there is a need suddenly to accelerate the process, to send a signal to our service members that the assessment is nothing more than eye wash, is beyond me.”

The GOP Senators’ comments came as Lieberman’s proposal gained traction with members of the Armed Services panel. A Democratic holdout, Sen. Ben Nelson (Neb.), declared Wednesday he will support the amendment, as did moderate Republican Sen. Susan Collins (Maine).

Nelson said in a statement that he made his decision after talking with Defense Secretary Robert Gates, who has grudgingly signed off on compromise repeal language.

“In a military, which values honesty and integrity, this policy encourages deceit,” Nelson said.

Webb Opposed to Amendment

Collins’ vote would effectively cancel out the opposition of the one Armed Services Democrat, Sen. Jim Webb (Va.), who as of Wednesday afternoon was publicly opposed to Lieberman’s amendment.

The amendment would delay implementation of the change until after a Pentagon review is finished and make it contingent on certification from the president and top military officials that repeal would not adversely affect military readiness.

Opponents argue for awaiting the Pentagon review before Congress takes action, and a GOP leadership aide predicted that Republicans would “take steps to change the language” if it makes it to the floor, adding that it was premature to talk specifics other than to say the argument likely “will include the point that the military hasn’t yet concluded their study on how the change might affect readiness.”

The vote of one Democrat on the panel, where the majority enjoys a four-seat edge, remained in doubt as of press time. Sen. Evan Bayh (Ind.) said he was “looking at the compromise” to ensure it took into account “the practical recommendations of the military” on how to go about repeal. Sen. Robert Byrd (W.Va.) announced his support late Wednesday.

All other Democrats on the panel are expected to support the amendment.

“We are increasingly confident about the Lieberman compromise and that this could very well be a historic week in the United States Congress,” Lieberman spokesman Marshall Wittmann said Wednesday afternoon.

If the repeal is adopted in committee, it would significantly boost its chances of being in the final version of the legislation, because opponents likely would need 60 votes to strip it. Failing that, opponents would then be in the uncomfortable position of deciding whether to vote against the wide-ranging defense authorization bill, which usually draws broad support from both sides of the aisle.

Aubrey Sarvis, executive director of the Servicemembers Legal Defense Network, predicted Republicans would not follow through with filibuster threats.

“That’s a decision they’ll have to make in late June or July when the bill is called up on the floor of the Senate,” Sarvis said. “It’s rather extraordinary to filibuster the defense authorization bill. … Even if they make the threat, I would assert that they could not sustain a filibuster.”

Reid Vows Support on Floor

Majority Leader Harry Reid said Wednesday that he was committed to trying to include the repeal language in the bill that passes the Senate.

“If it’s in the committee, of course,” the Nevada Democrat said, noting that he is a longtime advocate of repealing the policy. “If it isn’t, there will be an amendment anyway.”

Reid’s comments also could help shore up support for repeal in the House, where a floor vote that had been planned for this week may slip until after the Memorial Day recess because of snags with a broad tax extenders package.

Rep. Patrick Murphy (D-Pa.) has been the lead House proponent of repeal and has repeatedly insisted it has enough support to prevail in the chamber.

Sarvis said a majority of House Democrats favor repeal and predicted that Murphy’s language would be adopted, regardless of whether the vote is before or after Memorial Day.

“Even if under the worst scenario, if they don’t get it in this week … I don’t think it matters,” he said.

Tory Newmyer contributed to this report.