Senators Susan Collins of Maine, Joe Lieberman of Connecticut, Kirsten Gillibrand of New York and Mark Udall of Colorado have introduced a stand-alone bill to repeal the military's ban on gay and bisexual troops serving openly.

The senators introduced the bill (S4022) on Thursday shortly after Republicans blocked a defense spending bill which includes the repeal measure from moving forward.

Senate Majority Leader Harry Reid attempted the vote after several moderate Republicans hinted they might support repeal. Only Collins crossed the aisle to vote with all but one Democrat, West Virginia Senator Joe Manchin. Blanche Lincoln, a senator from Arkansas who voted against the measure in September, arrived too late to cast her vote, but told reporters that she would have voted for repeal.

“The reality remains that 60 – and I think maybe more than 60 – members of the United States Senate have made clear that they support the repeal of 'Don't Ask, Don't Tell,'” Lieberman said in introducing the bill. “We're going to keep fighting until the last possible moment in this session. Because we've got the votes to change this unjust policy and we owe it to ourselves and to our country.”

Lieberman told reporters that the bill enjoys the support of Senator Reid.

Reid “said, 'I will bring it to the active calender under rule 14,'” Lieberman said, referring to a Senate rule that allows a measure to bypass a committee hearing.

Appearing on MSNBC's The Rachel Maddow Show, Aubrey Sarvis, executive director of Servicemembers Legal Defense Network (SLDN), the largest group lobbying for repeal of the Clinton-era law, said the stand-alone effort had a “good” chance of passage.