US president Donald Trump's budget director and chief of staff yesterday said the partial government shutdown could continue to January 3, when the new Congress convenes and Democrats take over the House of Representatives.
"It's very possible this shutdown will go beyond the 28th and into the new Congress," Mick Mulvaney said on 'Fox News Sunday'.
"I don't think things are going to move very quickly here for the next few days" because of the Christmas holiday, added Mr Mulvaney, who serves as director of the Office of Management and Budget and was named acting White House chief of staff 10 days ago.
The US Senate adjourned on Saturday unable to break an impasse over Trump's demand for more funds for a wall on the border with Mexico that Democrats are unwilling to accept.
Mr Mulvaney said the White House made a counter offer to Democrats on funding for border security that falls between the Democratic offer of $1.3bn (€1.14bn) and Trump's demand for $5bn (€4.4bn).
As part of those talks on Saturday, Vice President Mike Pence offered to drop the demand for $5bn for a border wall, substituting instead $2.1bn (€1.84bn), reported ABC News.
Mr Mulvaney sought to shift blame for the partial shutdown to Nancy Pelosi, the Democratic nominee for speaker of the House of Representatives, saying she might hold up negotiations to ensure she secures the position.
"I think she's in that unfortunate position of being beholden to her left wing to where she cannot be seen as agreeing with the president on anything until after she is speaker," Mr Mulvaney said.
"If that's the case, again, there's a chance we go into the next Congress."
Financing for about a quarter of federal government programmes - including the departments of Homeland Security, Justice and Agriculture - expired at midnight on Friday and will not be renewed until a deal is done.
Federal parks were to close and more than 400,000 federal "essential" employees in those agencies will work without pay until the dispute is resolved. Another 380,000 will be "furloughed", meaning they are put on temporary leave.
Law enforcement efforts, border patrols, mail delivery and airport operations will keep running.
Building a wall to keep migrants from entering the United States illegally was a central plank of Mr Trump's presidential campaign, but Democrats are vehemently opposed and have rejected his funding request.
Mr Trump reiterated his push for border security yesterday, tweeting "the only way" to stop drugs, gangs, and human trafficking at the border was with a wall or barrier.
"Drones and all of the rest are wonderful and lots of fun, but it is only a good old fashioned Wall that works!" the president tweeted.
Meanwhile, Mr Trump said yesterday he would immediately replace outgoing Defence Secretary James Mattis with his top deputy, Patrick Shanahan, ending the former general's tenure two months before his planned exit from the Pentagon.
Mr Mattis announced his resignation last week in a lengthy letter underscoring his policy differences with the president, but stating he would stay on the job until February 28.
The retired Marine Corps general quit after Mr Trump announced his plans to immediately withdraw US troops from Syria.