President Trump has threatened to declare a national emergency if he is unable to make a deal with Democratic lawmakers to fund his border wall, though on Friday he said he was not going to do it "so fast because this is something Congress should do". He said that the ball was in the court of his political opponents, warning that "we will be out for a long time unless the Democrats come back from their "vacations" and get back to work".
The BBC's David Willis in Washington says that, with no further talks with the Democrats planned, this now seems the most likely option for the president.
Democrats and the president remain at loggerheads, with party leaders saying they won't agree to fund any kind of wall or barrier and Trump insisting he won't agree to reopen the government until the wall is funded.
As Friday ticked into Saturday, the shutdown passed the 21-day mark set when Bill Clinton faced a hostile Republican Congress in 1995 and 1996.
Government workers and supporters hold a protest rally in Boston as the partial United States government shutdown becomes the longest since 1995.
Desperate workers have shared appeals online or have started selling their possessions after paychecks failed to materialise.
One major airport, Miami International, said it would close an entire terminal this weekend because so many security staff are off sick.
On Friday, government workers missed their first payday of this shutdown.
The head of the U.S. Secret Service, which is responsible for protecting Trump, has warned employees that financial stress can lead to depression and anxiety. "Keep an eye out for warning signs of trouble", Director R.D. "So what we are proposing is to build the infrastructure of the ports of entry...to have the scanning technology to scan cars coming through, for drugs, contraband of any kind, weapons even".
"T$3 here are 800,000 federal employees who didn't get a check yesterday", Pirro said to Trump.
Trump, according to the Associated Press, said he was not looking to declare an emergency to build a wall "right now", contending that "this is something Congress can do".
Trump insisted there is absolutely no chaos in the White House, saying, "There's nearly nobody in the W.H. but me".
Trump met with Democratic and Republican congressional leaders at the White House this past week. "I am in the White House ready to sign!" But the legislation has been ignored by the Republican-controlled Senate.
Separately, Puerto Rico's governor urged Trump to not redirect emergency funds from projects to help the storm-ravaged island to wall construction along the US-Mexico border. But Mexico has refused.
About a quarter of the federal government will go without funding until a budget is agreed, leaving 800,000 employees without pay. Funding for other portions of the government, including the Department of Defense and Congress, was approved, allowing them to continue regular operations.
"Democrats should come back to Washington and work to end the Shutdown, while at the same time ending the awful humanitarian crisis at our Southern Border", Mr. Trump tweeted.
Fight for the Future pointed to border surveillance programs that already exist and "desperately need Congressional review" instead of being expanded, includingsearches of electronic devicesandmonitoring by drones.
Progressives in recent weeks have applauded Democrats' refusal to bend to President Donald Trump's demands for a wall at the US-Mexico border, a key component of his xenophobic anti-immigration agenda.