Updated

4:32 p.m., Feb. 6: It's very tough to get a read on when and whether the Senate might vote on the economic stimulus package, because much of the negotiating is going on behind closed doors with staff kicked out.

Senate Minority Leader Mitch McConnell's lead counsel tells FOX News they won't finish tonight.

But that's not in stone. Majority Leader Harry Reid's staff is trying to negotiate with McConnell -- and there's a slim chance they'll wrap up everything in the wee hours.

Sen. Jon Kyl, R-Ariz., just said even if Democrats do reach an agreement tonight, he thinks Republicans will want more time.

A big meeting just started in Reid's office. Moderate Democratic Sen. Ben Nelson, Sen. Arlen Specter, R-Pa., and Sen. Susan Collins, R-Maine, have gone inside as they try to negotiate a compromise. There's word White House Chief of Staff Rahm Emanuel is now inside.

Reid is desperately seeking at least two Republicans -- and now there is also word that Democratic Sen. Ted Kennedy, Mass., is going to have to return for the vote.

3:40 p.m., Feb. 6: Lead Senate GOP negotiator Susan Collins of Maine emerged from a meeting with Senate Majority Leader Harry Reid, D-Nev., without a smile. Asked how she felt about reaching a consensus on passing a stimulus bill, she said through gritted teeth, "Not as good as I felt earlier."

Sen. Arlen Specter, R-Pa., one of three Republicans who are thought to be possible "yes" votes on the end product, left the meeting with Collins and had no comment.

Collins said Reid made a counterproposal.

"We'll look at it," she said.

Meanwhile, Senate Democrats were preparing for a special meeting of the entire caucus to discuss the way forward.

11:33 a.m., Feb. 6: Coming up with a stimulus bill that can pass the U.S. Senate is becoming a monumental task.

President Obama has held one-on-one meetings with negotiators of a compromise bill; he and his aides have been working the phones, with many paying multiple visits to Capitol Hill. And last night, he burned the near-midnight oil talking with Senate Majority Leader Harry Reid, with Obama Chief of Staff Rahm Emanuel participating as well.

"They were on the phone until 11:30 p.m. last night," a senior aide to Reid tells FOX News.

Bipartisan negotiators, led by Sens. Ben Nelson, D-Neb., and Susan Collins, R-Maine, are trying to find the sweet spot, which appears to be in favor of cutting between $75 billion and $80 billion. That would leave the bill, with home and car buying tax cuts included, at about $857 billion.

Reid is making calls to his members now, according to staff, to talk to them about what is being taken out of the bill, to assuage concerns when they learn their special projects have been nixed. Senate staff is being briefed on what has been cut, so more and more concerns are coming to light.

Sen Dick Durbin, D-Ill., said "the most painful cuts" are to education and aid to states.

Reid said he hopes to have a vote tonight, between 5 p.m. and 7 p.m., on the compromise.

Originally, the negotiators were trying to cut more than $100 billion, but that has proved too much for some Democrats.

Reid is said to be looking for three Republicans to support the final bill.

One such Republican, George Voinovich, R-Ohio, said he is very concerned about education funding being included.

10:40 a.m., Feb. 6: Sen. Dick Durbin, D-Ill., the Senate Democrats' No. 2 leader, told FOX News "the two most painful areas" where negotiators are making cuts is aid to the states and education funding -- much of that is for construction.

Asked if he can get his members on board if the cuts are as high as $100 billion, Durbin said, "I just don't know."

He said they have not reached a deal yet.

9:45 a.m., Feb. 6: An aide to Sen. Johnny Isakson of Georgia, who proposed adding the $15,000 homebuyer tax credit to the stimulus plan, told FOX News that the Joint Committee on Taxation made a mistake with regard to the total cost of the amendment.

The committee revised its original estimate of $18.9 billion for the housing tax credit to $35.5 billion because it failed to account for the fact that a homebuyer could split the tax credit over two years, the aide said.

That raises the total cost of the stimulus package to $937 billion from about $925 billion.

"Sen. Isakson thinks it's important to give individuals the ability to claim the credit over two years so middle class taxpayers who have less than $15,000 in one year in tax liability will be able to take advantage of the credit," the aide said.

"He believes the new cost does not change the merit of the payback we will get in the housing market and he still stands by the viability and vitality of the amendment," the aide added.

9:20 a.m., Feb. 6: Moderate Senate Republicans are about to start a meeting in Sen. Arlen Specter's hideaway in the Capitol.

Aides to a few Republicans in the talks told FOX News no consensus has been reached, sounding a bit downbeat. But Reid only needs about three Republicans to sign on. He should be able to bring along his caucus -- if the cuts aren't too deep.

At this point, it appears it will be another long day.

7:40 a.m., Feb. 6: Despite vowing to "burn the midnight oil" to get an economic stimulus bill passed, Senate Majority Leader Harry Reid adjourned the Senate Thursday night shortly after 9 p.m. -- without enough votes for passage.

The Senate will reconvene Friday at 10 a.m. ET and cast early votes on more amendments to the 750-plus-page bill. At this point, Reid appears to be just buying time for the compromise group. He may have to file cloture on the bill, and this, too, would buy more time.

It would set up a key procedural vote for Sunday, but it's possible the group led by Sen. Ben Nelson, D-Neb., and Sen. Susan Collins, R-Maine, could produce a bill Friday and get a vote on the same day. This is a "Herculean effort," as lead negotiator Sen. Ben Nelson of Nebraska has said.

If a compromise is produced, Reid would try to hold not only a vote on it Friday, but also a final passage vote on the entire bill. Reid will also need to have a vote to add on what the Senate has already passed: about $30 billion in tax credits to encourage car and home buying. (Nelson-Collins will be a full substitute bill; it doesn't have the added credits, so they must be added on the floor).

Negotiators continue to work furiously to find "the sweet spot," as one participant, Sen. Joe Lieberman of Connecticut, said -- as most Republicans are fuming that they've had no hand in crafting this bill. Such is life in the minority party. (It is unclear where or when they are meeting Friday morning, but staff worked through the night.)

Reid had to give the "Gang of 18" more time, because he knew he didn't have 60 votes to pass any bill.

The group is getting closer. They've targeted about $90 billion in cuts to the now $920 billion bill on the floor, but they hit a rough patch with some Democrats, as deep cuts to energy renewables and not enough for infrastructure proved unpalatable for many.

Some senior Senate Democratic leadership aides are saying "the sweet spot" will be found at about $75 billion to $80 billion in cuts, but that means Reid will only limp across the finish line with barely any GOP support, maybe just two or three Republicans, depending on if the ailing Sen. Ted Kennedy, D-Mass., is able to show up to vote. GOP negotiators, like Mel Martinez, said the education spending does not belong in the bill..

Democratic aides say Reid is looking at Republicans: Arlen Specter, George Voinovich, Olympia Snowe, and possibly lead GOP negotiator Collins, though Collins is looking to see the topline total of the bill get down to $800 billion. Reid might not be able to count on her.

The interesting thing here --- Obama has endorsed cutting out more than $100 billion, according to Collins, Snowe and Nelson, all of whom have had one-on-one meetings with the president. Is this causing problems? Seems so. These kinds of cuts might lose Democratic support, according to one senior Senate Democratic leadership aide.

It's a very delicate balancing act, but Collins appears to be right when she told reporters Thursday, in reaction to Reid's blustery warning about overreaching: "I would say to the majority leader that his success depends upon the success of this group."