The Senate met privately Monday evening at the Capitol, but emerged without a deal to avert the so-called nuclear option that would curtail the minority's ability to filibuster presidential nominees.

The Senate will now continue as planned with votes on seven stalled executive branch nominees, with Senate Majority Leader Harry Reid's threat to change the body's rules hanging over the proceedings. Members of both parties said that negotiations toward a bipartisan solution would continue.

"We had a pretty good conversation; the conversation will continue tonight. Votes are scheduled for 10 o'clock in the morning," Reid, D-Nev., told reporters after the meeting.

Sen. John McCain, R-Ariz., who is acting as the ringleader of an informal group of senators who are looking for a way to avoid the nuclear option, said that they were "still working, still working away, still discussing options. ... We're going to continue to negotiate and continue to talk."

But other senators described the three-hour meeting as long-winded, repetitive and ultimately unsuccessful.

The challenge to reaching a deal is crafting an accord that gives something to the Republicans in exchange for backing off of their filibuster of key administration nominees. According to a Republican senator who was present for last night's meeting in the old Senate chamber, that remained the sticking point as the session broke up at around 10 p.m. Eastern Time.

"Republicans focused on not breaking the rules to change the rules," this senator said, of a private meeting that most members declined to discuss upon exiting the room. "Reid indicated he will call it off if he gets all 7 nominations confirmed.  He wants 6 Rep votes to get cloture on all nominations.  Reid wouldn't agree to new NLRB nominations or to not change the rules for the duration of this Congress.  At present, it appears to be a stalemate unless GOP gives Democrats 6 votes on these nominations — everything Reid came into the meeting demanding."  

"We'll see if anything breaks by the morning," this GOP senator added, explaining that many Democrats argued that the constant GOP filibusters have contributed to Congress' low approval ratings.

Sen. Lamar Alexander, R-Tenn., who has worked with Democrats in the past to defuse tensions over the GOP's use of the filibuster, said he does not believe enough Democrats are interested in avoiding Reid's proposed rules change.

"I don't feel very good about [it], to tell you the truth," Alexander said. "I'm glad we had the meeting; I appreciate it. But there are too many senators who don't understand the danger of the precedent of a Senate that can change the majority any time it wants to."

Sen. Tom Harkin, D-Iowa, a longtime proponent of weakening the filibuster, said, "My hope is that we get rid of the filibuster for executive branch nominees. Let's get this over and done with."

The unusual, closed-door, joint caucus of Democrats and Republicans was viewed as an attempt to negotiate a bipartisan agreement to resolve differences over the use of the filibuster.

Democrats charge that Republicans have been abusing the parliamentary procedure to unfairly block President Obama's cabinet and executive branch agency nominees. The GOP counters that the majority has trampled on their rights in contradiction of Senate traditions.

Reid is threatening to change Senate rules so that only a simple majority -- rather than the 60 votes now required -- are needed to advance nominees. That would allow Democrats, who control 54 Senate seats, to act without consideration to Republicans.

Sen. Roger Wicker, R-Miss., held out hope that "this could be worked out, even yet," telling reporters the two parties had been "very close" over the weekend before talks had broken down.

"There was a consensus that the leadership would continue to work, and I believe they will," he said.

In brief interviews with senators as they exited the meeting, it still appeared as though the chamber was on a collision course over a rules change that could have broad implications for how the chamber functions in the future.

Reid will call this week for series of votes on Obama nominees that Republicans have been delaying for months, including one to head the Consumer Financial Protection Bureau created by the Dodd-Frank legislation, and a several to the National Labor Relations Board.

If completed, the rules change would not apply to judicial nominations.