(CNN) - Senate Majority Leader Mitch McConnell announced Sunday evening that leadership from both chambers have reached a deal on "a package of nearly $900 billion" of much-needed relief for the Covid-19 pandemic, though Congress still faces a government shutdown deadline at midnight.
"Moments ago, in consultation with our committees, the four leaders of the Senate and the House finalized an agreement," McConnell, a Kentucky Republican, said on the Senate floor. "There will be another major rescue package for the American people."
The exact details of what was in the bill and when Congress would vote was not immediately clear, and whether it will happen in time to avoid the government shutting down remains unknown.
A late-night Saturday breakthrough to resolve a key dispute holding up a rescue package signaled major progress toward a deal, but congressional leaders have been trying to hammer out the final details of an agreement and there are still some outstanding issues. As a result, it has taken much of the day Sunday to iron out the last disagreements before finally unveiling the text to the rest of Congress shortly before votes occur, aides said Sunday.
House Speaker Nancy Pelosi still wants a vote Sunday night, as does Senate Minority Leader Chuck Schumer, but Republicans believe another stopgap measure will be needed to avoid a midnight shutdown and they should vote Monday instead.
The relevant committees of jurisdiction are now finalizing the bill text and are getting official cost estimates with the Congressional Budget Office -- a process that takes time to play out.
McConnell said earlier Sunday that "we appear to be just hours away" from finalizing an agreement, while Schumer said, "It appears that barring a major mishap the Senate and House will be able to vote on final legislation as early as tonight."
It's far from certain that will happen, however, and other prominent lawmakers have suggested the timeline could slip.
Top Republican Sen. John Cornyn of Texas told reporters he thinks "it's doubtful" the Senate will vote Sunday on a stimulus package -- and they'll likely need to pass a stopgap bill known as a continuing resolution to extend the government funding deadline.
The amount of work that still remains to be done and the looming midnight deadline increases the odds that a sweeping pandemic deal may not be finalized and approved in time to avert a shutdown this evening.
If finalizing the bill drags on Sunday, as many expect, Congress may -- for the fourth time since September -- be forced to pass a stopgap spending bill to avoid a government shutdown. It's possible, one source said, they may have to pass a one-to-two day stopgap.
What could be in the package?
Lawmakers also have not yet seen the text of a $1.4 trillion omnibus spending package that leaders are trying to push through to fund the government through next September. The goal is to tie the Covid-19 relief bill to the massive omnibus package.
With the holidays and the end of the 116th Congress rapidly approaching, lawmakers are facing intense, and growing, pressure to finalize and approve what is expected to be a $900 billion relief deal with $300 per week in jobless benefits, direct payments of $600 for individuals, $330 billion for small business loans, more than $80 billion for schools, and billions for vaccine distribution.
For now, the two sides are still going back-and-forth over a handful of outstanding issues, including how private schools should be treated in the more than $80 billion in aid outlined for schools and education providers. Republicans had been pushing for $5 billion in aid for private schools -- but Democrats had tried to cut that to be about $2.5 billion, according to a source with direct knowledge of the talks.
Sen. Roy Blunt, a member of the GOP leadership, confirmed that how to "treat private schools" is one of the final issues to iron out.
Other details about the emerging proposal include enhanced jobless benefits at $300 per week that would begin on December 27 and go on for about 11 more weeks, according to a source with knowledge of the discussions. That is less than what many Democrats wanted but more than what many Republicans were willing to support.
Also, direct payments would indeed be capped at $600 per person for an individual earning less than $75,000. The proposal would provide an additional $600 per person in the family, meaning a family of five could get $3,000 assuming they're under the requisite income threshold.
There has been late discussion about providing more money for restaurants and for live performance venues -- something that has bipartisan support.
The proposal also is expected to help provide aid to farmers, bolster money for the nation's food supply, increase money for food stamps and provide more for nutrition assistance -- while providing additional funds for community health centers to help with mental health problems.
Congressional procedure could slow passage
Even after a package is finalized, a number of procedural steps still need to take place to clear the way for a vote in both chambers, with the potential to further slow the process.
Once the text is unveiled, the House Rules Committee will have to consider the package -- a meeting that could take several hours. Then, they will have to schedule a House floor debate and set up votes in the chamber.
The Senate is more complicated because it requires consent of all 100 members to schedule a vote, and it's uncertain if that will happen if any member is unhappy with the bill or the process. If they can't get an agreement for a quick vote, Senate Majority Leader Mitch McConnell will be forced to take procedural steps to up a vote, a process that could take several days.
Hill leaders have been saying for days that a deal is close at hand, a promise that was reiterated last night after Democrats and Republicans reached an apparent resolution to a contentious partisan dispute over the role of the Federal Reserve to intervene in the US economy.
Following tense negotiations over a provision pushed by Sen. Pat Toomey to pare back the role of the central bank's emergency lending authority, Senate Minority Leader Chuck Schumer and the Pennsylvania Republican reached a deal in principle over the provision, aides said. Now, the two sides will draft the legislative language to ensure it reflects the outlines of the deal.
"We're getting very close, very close," Schumer said as he left the Capitol, predicting the House and Senate would vote to approve the package Sunday -- just hours before the government runs out of money at midnight. McConnell's office also said a deal was in sight.
But there are still a series of hurdles congressional leaders will now have to confront -- from locking down the details of the package to pushing for a quick vote -- to get a package over the finish line.