Parts of the U.S. government began shutting down on Saturday for the third time this year after a bipartisan spending deal collapsed over President Donald Trump’s demands for more money to build a wall along the U.S.-Mexico border.

Trump scuttled an agreement that would have kept the government open until February after coming under heavy criticism from conservative talk show hosts and some allies in the House because the measure didn’t include the US$5 billion he wanted for the wall. While negotiations to resolve the impasse are underway, it’s not clear whether parts of the government will remain shuttered for days or weeks.

Ending the shutdown -- which affects nine of 15 federal departments and dozens of agencies -- requires Democratic leaders and Trump to reach a compromise, which so far has been elusive as both sides hardened their positions. The House and Senate are scheduled to convene at noon on Saturday, but lawmakers were told they’ll be given 24 hours notice of any planned votes.

The failure of elected officials to keep the government fully operating caps a chaotic week in Washington, during which Trump announced a withdrawal of all U.S. forces from Syria, a draw-down of U.S. forces in Afghanistan, and the resignation of Defense Secretary Jim Mattis.

Negotiations between the White House and Democrats went on into Friday night. Trump’s emissaries were Vice President Mike Pence, White House budget director Mick Mulvaney and senior adviser Jared Kushner, who shuttled between private meetings with lawmakers on Capitol Hill.

Senator Richard Shelby of Alabama, chairman of the Appropriations Committee, said Republicans made an offer on a funding measure and were waiting for a response from Senate Democratic leader Chuck Schumer of New York.

"I am hopeful," he said of the negotiations. "We’ve made some overtures."

Talks revolved around providing less money for border barriers and more restrictions than Trump initially demanded.

Congressional leaders said they wouldn’t call lawmakers back for votes until both chambers and the White House had an agreement on how to end the dispute. The two previous shutdowns earlier this year were short-lived and were over issues including immigration and spending levels.

Sudden Change

The blow-up was sudden. On Wednesday, the Senate easily passed a temporary spending measure without any money for the wall after getting signals from the White House that Trump wouldn’t press the issue and trigger a shutdown. But after the outcry from conservatives, the House, at Trump’s insistence, amended it a day later to include US$5 billion for the wall. That was unacceptable to Democrats who have enough votes in the Senate to block the legislation.

On Friday, senators who had left town were summoned back to Washington to vote on the plan as amended by the House. At first, GOP leaders in the chamber struggled to muster enough support for the House plan to move forward. That led to negotiations with the White House. The Senate eventually voted to begin debate, but agreed to wait for a bipartisan agreement before moving any further.

John Cornyn of Texas, the No. 2 Senate Republican, said a potential deal could include US$1.6 billion for border security, slightly more than Democrats were offering in recent weeks. It wasn’t clear whether Trump would accept that amount or if Democrats would agree to more than the US$1.375 billion they’d previously offered.

"This isn’t rocket science to try to come up with a figure," Cornyn said.

Talk Radio ‘Tyranny’

Republican Senator Bob Corker of Tennessee, who has traded barbs with the president in the past, faulted Trump over pushing to shut the government at the urging of commentators who have told him to stand up to Democrats.

"This is tyranny of talk radio," said the retiring senator. "How do you deal with that? Tyranny of talk radio. Two talk radio hosts completely flipped a president."

As the standoff dragged on, Trump went on the attack.

"The Democrats, whose votes we need in the Senate, will probably vote against Border Security and the Wall even though they know it is DESPERATELY NEEDED," Trump said in a Friday morning Twitter post. "If the Dems vote no, there will be a shutdown that will last for a very long time. People don’t want Open Borders and Crime!"

In a video posted on Twitter Friday evening, he appealed to Senate Democrats: "We have a wonderful list of things that we need to keep our country safe. So let’s get out. Let’s work together. Let’s be bipartisan and let’s get it done. The shutdown hopefully will not last long."

But the Democrats, along with some Republicans, said they couldn’t support the US$5 billion sought by Trump because they said a wall was an ineffective and inefficient method of securing the border.

No Wall

Schumer and House Democratic leader Nancy Pelosi of California, who is likely to become speaker when her party takes control of the chamber, said in a joint statement released early Saturday that the president "threw a temper tantrum and convinced House Republicans to push our nation into a destructive Trump Shutdown in the middle of the holiday season."

"Democrats have offered Republicans multiple proposals to keep the government open," the two leaders said, "including one that already passed the Senate unanimously, and all of which include funding for strong, sensible, and effective border security – not the president’s ineffective and expensive wall."

Trump last week met with Pelosi and Schumer in front of television cameras and said he’d be proud to take responsibility for shutting down the government over border protection funding. But on Friday, he was blaming Democrats for the impasse.

The nine departments that will shut down early Dec. 22 represent about a quarter of the US$1.24 trillion in government spending for fiscal year 2019. The remaining three-quarters of the government, including the Defense Department, Departments of Labor and Health and Human Services, were already funded and won’t be affected by the shutdown.

The Department of Veterans Affairs will also not be affected, according to a statement from VA Secretary Robert Wilkie. The Department of Transportation would keep about two-thirds of its more than 50,000 employees on the job.

An estimated 400,000 federal employees would work without pay and 350,000 would be furloughed, according to a congressional Democratic aide. The essential employees who work during a shutdown are paid retroactively when the government reopens and payroll operations resume. After previous shutdowns, Congress also has passed legislation to retroactively pay furloughed workers.

The 16-day full government shutdown in October 2013 cost the economy US$24 billion, according to Standard and Poor’s.