WASHINGTON (BLOOMBERG) - Lawmakers signalled a United States government shutdown is likely to last past Christmas, as the White House and Democrats remained far apart in negotiations over President Donald Trump's demand for border wall funding.

Senate Majority Leader Mitch McConnell said the Senate would adjourn for regular business until Thursday (Dec 27), but told reporters not to interpret that to mean negotiations have stalled.

Ms Nancy Pelosi, the top Democrat in the House, warned that the shutdown may not be resolved until early January, when her party takes control of the chamber.

Vice-President Mike Pence returned to the US Capitol on Saturday to make an offer to the chamber's top Democrat, Mr Chuck Schumer of New York, said Senate Appropriations chairman Richard Shelby of Alabama.

But after the meeting, a spokesman for Mr Schumer said the two sides were far from an agreement.

"We're still talking," Mr Pence said when leaving Mr Schumer's office. "We'll keep you posted."

Even as Mr Pence arrived, both sides dug into their positions over the terms of reopening the nine government departments that ran out of funding on Saturday.

"If you want to open the government, you must abandon the wall," Mr Schumer said on the Senate floor on Saturday. He described the wall as a "bone to the hard right".

A senior Trump administration official told reporters on a conference call that Democrats must accept physical barriers as part of any deal. Mr Trump would be willing to negotiate the type of barrier and restrictions on where construction could occur, the official said.

"I won an election, said to be one of the greatest of all time, based on getting out of endless & costly foreign wars & also based on Strong Borders which will keep our Country safe," Mr Trump tweeted.

"We fight for the borders of other countries, but we won't fight for the borders of our own!"

Several Republican lawmakers, including Mr Shelby, Senator Lindsey Graham of South Carolina, and four representatives from the conservative House Freedom Caucus went to the White House to meet Mr Trump and Mr Pence about border security.

Scuttled Agreement

Mr Trump scuttled an agreement earlier last week that would have kept the government open through Feb 8 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 (S$6.8 billion) he wanted for the wall.

While negotiations to resolve the impasse are continuing, 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, dozens of agencies and hundreds of thousands of workers - would also require the support of Ms Pelosi of California, who is in line to become speaker on Jan 3.

"Until President Trump can publicly commit to a bipartisan resolution, there will be no agreement before January when the new House Democratic Majority will swiftly pass legislation to re-open government," Ms Pelosi said in a letter on Saturday (Dec 22) to fellow Democrats.

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

Stocks dropped sharply last Friday as a shutdown looked inevitable.

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

Mr Trump stopped talking about a concrete wall in recent weeks and focused on building a more fence-like steel structure. A deal with Democrats could revolve around allowing funds to be used for that kind of structure.

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. Mr Schumer has told Mr Pence that Mr Trump must publicly back any deal before it comes to a vote, according to a Senate Democratic aide said.

If a deal isn't done before Jan 3, when Democrats take control of the House, negotiations may become more difficult for Mr Trump.

Sudden Change

Last week's blow-up was sudden. Last Wednesday, the Senate easily passed a temporary spending measure without any money for the wall after getting signals from the White House that Mr Trump wouldn't press the issue and trigger a shutdown.

But after the outcry from conservatives, including talk show host Rush Limbaugh, the House, at Mr 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.

Last 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.

Mr 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 Mr 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," Mr Cornyn said.

Talk Radio 'Tyranny'

Republican Senator Bob Corker of Tennessee, who has traded barbs with the president in the past, faulted Mr 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."

In a video posted on Twitter last Friday evening, Mr Trump appealled 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 Mr Trump because they said a wall was an ineffective and inefficient method of securing the border.

No Wall

Mr Schumer and Ms Pelosi 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".

Mr Trump last week met with Ms Pelosi and Mr 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 last Friday, he was blaming Democrats for the impasse.

The two previous shutdowns earlier this year were short-lived and were over issues including immigration and spending levels.

The nine departments that will shut down early on Saturday represent about a quarter of the US$1.24 trillion in government discretionary spending for fiscal year 2019. The remaining parts of the government, including the Defence Department, Departments of Labour and Health and Human Services, were already funded and won't be affected by the shutdown, nor with mandatory entitlement programmes like Social Security payments.

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 will work without pay and 350,000 will now 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.