The US government was partially shut down early on Saturday in a fierce dispute over President Donald Trump's demands that Congress assign $5 billion for a wall along the border with Mexico.
After failing to strike a budget deal on Friday, congressional leaders and the White House pledged to keep talking through the weekend in search of a deal to end the shutdown ahead of the Christmas holiday.
The impasse came after Trump threw a wrench into the works earlier in the week by refusing to agree to a short-term funding deal cut by Democratic and Republican senators because it did not include the $5 billion for his border wall.
The US House of Representatives, where Republicans have a majority until Democrats take over on January 3, then passed a bill that including the $5 billion, but it ran aground in the Senate and the shutdown began at midnight on Friday.
After it became clear the House bill lacked the votes to pass, Senate leaders huddled with Vice President Mike Pence and other White House officials to try to figure out a path forward.
They failed and lawmakers in both houses of Congress were sent home.
Trump tried to blame Democrats.
"We're going to have a shutdown. There's nothing we can do about that because we need the Democrats to give us their votes," he said in a video posted to his Twitter account two hours before the midnight deadline.
"The shutdown hopefully will not last long."
It remained unclear how long the shutdown will last. But the optics are bad, as hundreds of thousands of federal employees will be either furloughed or forced to work without pay in the run up to the Christmas holiday.
The House is due back in session at noon Saturday.
The Senate meanwhile remained open late Friday, but there were no signs yet of a breakthrough, and the chamber was quiet.
Senators told reporters that congressional leaders from both parties were negotiating behind the scenes with White House officials including Vice President Mike Pence, Trump's son-in-law Jared Kushner, and incoming chief of staff Mick Mulvaney.
One focus of discussion was the $1.6 billion in border security funding that was a part of pending Senate legislation, number two Senate Republican John Cornyn told AFP.
But conservatives in the House would likely balk at that figure.
"There's no agreement," congressman Mark Meadows, chairman of the House Freedom Caucus of ultra-conservatives, told reporters as he made his way from Senate meetings to the House.
"There's a whole lot of numbers being thrown around," but a maximum $1.6 billion for border security "is not acceptable."
Trump was scheduled to fly to Florida late Friday for his Christmas break, but the White House said the president postponed the trip and would remain in Washington in an effort to salvage a spending deal.