Congressional bickering over a new economic relief package escalated Thursday as lawmakers traded blame and put negotiations over critical legislation on the brink of collapse.

And the finger-pointing even threatened to imperil a must-pass spending bill in the Senate, as lawmakers were still unsure whether they would be able to pass a measure by a deadline Friday night to avert a government shutdown.

The worsening situation came as multiple lawmakers appeared to be pursuing conflicting goals, with little time to sort out disagreements. The House passed a spending bill Wednesday to fund the government for one week and avoid a shutdown deadline Friday night. The Senate must pass an identical bill — and have President Trump sign it — to avoid a shutdown, but as of Thursday afternoon, lawmakers still weren’t sure how to do that with unanimous consent.

Meanwhile, House Speaker Nancy Pelosi (D-Calif.) suggested Thursday that discussions over emergency legislation could stretch beyond Christmas, even though multiple critical programs expire at the end of this month and there are fresh signs the economy is weakening. The Labor Department on Thursday announced that 853,000 Americans filed jobless claims last week, a big increase from the week before and a sign that the economy could be sliding backward as coronavirus cases pile up.

Further adding to the confusion, Sens. Bernie Sanders (I-Vt.) and Josh Hawley (R-Mo.) on Thursday threatened must-pass government spending legislation in an attempt to force congressional leadership to allow a vote on another round of $1,200 stimulus checks next week.

“We will not leave this town until we have voted, up or down, on direct relief for working people,” Hawley said in a speech on the Senate floor alongside Sanders.

Hawley later told reporters that he would not block the one-week government spending bill this week but did not rule out doing so next week. Asked by reporters if he would block Friday’s vote on legislation to avert a government shutdown, Sanders said: “We will play it by ear. Let me just repeat: I will do everything I can to make certain that we do not leave here until that bill is passed.”

Staffers for Senate Majority Leader Mitch McConnell (R-Ky.) also told leadership offices in both parties Wednesday night that McConnell sees no possible path for a bipartisan group of lawmakers to reach an agreement on two contentious provisions that would be broadly acceptable to Senate Republicans, according to a senior Democrat familiar with the negotiations.

McConnell has repeatedly emphasized that he thinks more assistance is needed to help the economy, but he has framed the emerging bipartisan package as unworkable.

His staffers warned that Senate Republicans would reject the group’s potential agreements on a temporary liability shield for businesses, as well as on aid to state and local governments — provisions that have complicated talks for months. The senior Democrat spoke on the condition of anonymity to discuss private deliberations.

In remarks on the Senate floor Thursday, McConnell repeated his demand for a broad liability shield for businesses and institutions vulnerable to coronavirus-related lawsuits and accused Democrats of “bullying small-business owners and college presidents who’ve been pleading for these protections for months.”

“I hope our colleagues let Congress deliver more help soon,” he said. “A lot of Americans simply cannot afford to wait.”

Several other signals suggested progress on providing emergency relief had petered out. Senate Minority Leader Charles E. Schumer (D-N.Y.) fiercely denounced McConnell’s proposed compromise measure to remove both state and local aid and the liability shield from the deal.

House Majority Leader Steny H. Hoyer (D-Md.) said House lawmakers would be sent home to their districts until a compromise measure was reached. It was unclear if Senate Republicans would be able on Thursday to approve legislation to keep the federal government funded for an additional week before it shuts down on Saturday.

The sudden disarray came just days after a bipartisan group of Senate lawmakers had hinted they were making major progress in brokering a targeted $908 billion stimulus plan, which would include some liability protections for businesses, new unemployment aid, and assistance for states and cities. Pelosi and Schumer had called the proposal encouraging and wanted to use it as the starting point for talks.

The bipartisan group of congressional lawmakers trying to break the logjam on stimulus has yet to announce a compromise on either the liability shield or the state and local aid funding. It has only issued the framework of an agreement, leaving many of the thorniest details unresolved.

Discussions were set to continue through the day Thursday, people familiar with the talks said, in hopes of striking at least a tentative deal by the end of the week.

But McConnell’s message to his counterparts Wednesday, as well as a Schumer speech Thursday casting doubt on whether combining state and local aid with liability shields is a fair trade-off, appeared to reduce the chances that the bipartisan group’s efforts could be the basis for a final deal.

“From everything I can pick up on, things are in a stalemate today,” said Bill Hoagland, a senior vice president at the Bipartisan Policy Center and former Republican staff director for the Senate Budget Committee. “But the desire is still there to get something put together on both sides. It’s always darkest before the sun rises.”

The pandemic is dealing severe blows to sectors of the American economy, and widespread distribution of a coronavirus vaccine remains months away.

At her news conference, Pelosi emphasized that President-elect Joe Biden would soon be sworn in and vowed that lawmakers could not go home until a deal had been reached.

“If we need more time, then we take more time. But we have to have a bill, and we cannot go home without it,” Pelosi said. “I would hope that it would honor the December 18th deadline. ... We’ve been here after Christmas, you know.”