(CNN) Lawmakers are pushing the federal government to the brink of a shutdown as they struggle to finalize a stopgap measure before funding runs out Friday at midnight.
The failure of congressional leaders to lock in a deal by now means that the only way to avoid a shutdown is for all 100 senators to agree to schedule a vote before the deadline. While lawmakers are confident they can ultimately prevent a prolonged shutdown, there are still sticking points to sort out as they scramble to finalize a funding agreement -- and a brief shutdown over the weekend, or extending into next week, remains a possibility.
Democrats and Republicans are grappling with disagreements over how long a funding extension should last. Negotiators are also facing a separate demand from Senate conservatives for a vote to defund the vaccine mandate that threatens to stall a quick vote in the chamber.
It is not yet clear when a deal will be reached and when the House and Senate will vote. As of Wednesday afternoon, congressional leaders still do not have an agreement on a stopgap resolution to keep the government open past Friday.
Congress is up against a government funding deadline lawmakers set for themselves earlier this year when both chambers passed a bill to extend funding through December 3. President Joe Biden signed that measure into law at the end of September.
Multiple GOP senators say that they ultimately plan to vote to keep the government open, so even if there's a shutdown, it would not be expected to last long.
Any one senator can object to a quick vote to keep the government open before the Friday deadline, and if one does once a deal is reached on a stopgap measure, there could be a brief shutdown through the weekend or into next week.
If there is an objection, that would force Senate Majority Leader Chuck Schumer to take time-consuming procedural steps to shut down debate.
Schumer outlined the challenge facing leadership on Wednesday.
"Every member can get up and say, 'I want a shutdown unless I get my way on something,'" he said. "We'll see what happens. It's up to the leaders to make sure there's not a shutdown. I'm making sure and I think Leader McConnell wants to try to make sure too. Let's hope."
A shutdown starting this weekend remains a possibility because some Republicans may slow walk Senate action if Democrats don't accept their demands.
If Republicans were to carry out all the procedural hurdles available to them -- and they have not said yet they will -- they could push passage of the spending bill until more than a week after the House eventually approves it and sends it to the Senate for action. The House has yet to schedule a vote.
If Republicans don't agree to speed up the process, Democrats would be forced to go through the time-consuming steps of breaking two GOP filibusters, one to begin debate on the House bill and the second to end it.
Each motion to break a filibuster must layover for one day after it is filed and can trigger up to 30 hours of additional debate once the 60 vote threshold vote to break the filibuster is achieved.
That could force a shutdown through next week, though that remains an unlikely scenario as of now.
Senate GOP leaders have made clear they don't favor a shutdown, but have yet to be able to convince some of their rank-and-file members to relent.
GOP Sens. Mike Lee of Utah and Roger Marshall of Kansas have demanded the funding resolution defund the Biden administration's vaccine mandate and have threatened to object to a quick vote without it. Republican Sen. Ron Johnson of Wisconsin supports their efforts as well.
At a closed-door GOP lunch, Marshall was one of just a small number of senators who spoke in favor of a strategy that could lead to a brief government shutdown. The other was Lee. An overwhelming number of Republicans spoke out against that strategy, multiple senators said.
Marshall told CNN that while he prefers the stopgap bill to include language prohibiting the Occupational Safety and Health Administration from enforcing the vaccine mandate on businesses, he would be satisfied with a vote on an amendment to that effect, assuming that passage of the amendment is set at a 51-vote threshold.
But since that would give it a chance at passage, Democrats are likely to insist that it be set at a 60-vote threshold.
Asked if he would object to a quick vote to pass the funding bill if the amendment were set at a 60-vote threshold, Marshall said: "We'll see. There's a long time between now and Friday. But ... I think at a minimum it deserves a 50-person vote."
During the GOP lunch on Wednesday, a number of senators told Marshall and Lee that little would be accomplished if there's a brief shutdown since the final bill would likely pass on Monday in any event -- and it won't defund the mandate.
Asked by CNN what the point would be of a brief shutdown that didn't accomplish his goals, Marshall said: "I think the folks back home want to know how hard we're fighting for them, that the jobs back home are as important as keeping the federal government open."
"That's the hypocrisy up here," he said. "It just seems like we have rules for back home that don't apply here. So I think that the federal government needs to feel the pressure of what a vaccine mandate really does."
Schumer said Wednesday afternoon that negotiations over funding the government beyond Friday's deadline continue "on a bipartisan, bicameral basis and we're making good progress," but he warned some Republicans are using "obstructive tactics that will make a government shutdown almost a certainty."
Senate Minority Leader Mitch McConnell vowed on Tuesday that there wouldn't be a shutdown. On Wednesday, he told reporters, "I think we're gonna be OK" when asked about the situation.
In one sign of stalled progress to lock in votes, however, House Majority Leader Steny Hoyer said in a closed-door meeting of House Democrats this morning that as of now, Democrats will not vote for a stopgap bill on Wednesday because McConnell will not agree to a date, according to a member in the room.
That comes after Hoyer indicated a day earlier that he had hoped to bring a bill to the floor Wednesday.
Later in the day on Tuesday, Hoyer blamed the Senate for the hold up, saying, "We're waiting for the Senate to decide what date they can agree on, which is ridiculous."
"The government is going to shut down in 72 hours and they can't get their act together," he said.
When the US government is within seven days of a potential shutdown, no matter the circumstances or state of play in funding negotiations, the Office of Management and Budget begins its standard shutdown planning protocol, reminding government agencies of the steps they should prepare to take. That protocol is in effect.
There is a plan in place for every government department and agency, all of which are laid out in significant detail on the OMB's website.
Those plans include information on how many employees would get furloughed, what employees are essential and would work without pay (for example, air traffic controllers, Secret Service agents, US Centers for Disease Control and Prevention laboratory staff), how long it would take to wind down operations in the hours before a shutdown, and what activities would come to a halt.
Government funding is only one of several time-sensitive policy issues that lawmakers must deal with in the coming weeks. There is also a looming debt limit deadline on December 15.
It is not yet clear how that issue will be resolved, but McConnell said on Tuesday that he believes there will not be a default and that he has been discussing a path forward with Schumer.
"First, let me assure everyone, the government will not default, as it never has. Second, the majority leader and I have been having discussions about the way forward," he said.
This story and headline have been updated with additional developments Wednesday.