That third Republican has since been revealed as Alaska Sen. Lisa Murkowski.
Lieberman has been the lead Dem negotiator for repeal, and has been in regular contact with all three Republican supporters. But earlier today his efforts were undermined, in his view, by Reid's announcement of a test vote tonight, and by leaks from the leadership, accusing Collins of demanding too many procedural concessions, putting the success or failure of the vote tonight at her feet.
From Reid's point of view the math is two-dimensional. By calling the vote, and leaking to the press, he ups the pressure on Collins to make a decision -- and quickly. At the same time, he creates a focal point for liberal animus if the Senate fails to pass repeal before this Congress comes to an end and with it hope for a legislative solution to DADT. That's not helpful to Lieberman, who wants to keep negotiations fluid, egos unbruised and the bill alive.
"That's why I think it would be so wrong to bring it up before they give us the time -- Senator Collins, others, myself -- to work out an amendment process," he told reporters.
Cooler heads could prevail. At a press conference today, a conciliatory Reid said discussions will continue this afternoon, but the vote, at least for now, is still on. Reid has offered to allow 15 votes on amendments if the Senate agrees to hold the debate tonight. Ten would go to Republicans, and five to Democrats.
"There was some stuff in the paper today that said she couldn't make up her mind what she wanted to do," Reid said. "That is really not true."
Afterward, though, a leadership aide told reporters the vote would go ahead tonight, even in absence of a deal.
"You've gotta call them on their stalling tactics," the aide said.
So the heat's on Lieberman -- and Collins, who is seen as key to getting Brown and Murkowski on board.
"I think we've got a shot to come to a process agreement today, which will enable us to have the 60 votes tonight," Lieberman said. "And if that happens, obviously I'm happy to have the votes."