White House officials and congressional aides are returning on Sunday to talks on how to get the government reopened after they wrapped up the first round without a breakthrough.

Senior Trump administration officials met Democratic congressional staffers but failed to break a deadlock on Saturday over a proposed border wall and end a two-week-old partial US government shutdown.

President Donald Trump tweeted: "Not much headway made today." The president later tweeted that he planned to go to his retreat at Camp David, Maryland, on Sunday morning to discuss borders security and other topics with senior staff at a separate meeting.

Vice President Mike Pence, who led the talks, posted on Twitter that the meeting was "productive" and both sides agreed to meet again on Sunday.

Negotiations have been at an impasse over Trump's demands for $5.6bn to fund a wall at the US-Mexico border.

On Friday, Trump declared he could keep the shutdown going for "months or even years".

Productive discussion w/ Congressional leadership staff at @WhiteHouse. @SecNielsen gave a full presentation on crisis along Southern Border. We reaffirmed @POTUS’ commitment to secure the border, build the wall, keep Americans safe & reopen gov’t. Discussions continue tomorrow. pic.twitter.com/C7k9Sg8guY — Vice President Mike Pence (@VP) January 5, 2019

Pence said in a statement after the meeting he had reiterated Trump's position that funding for the wall was needed, but he said: "there was no indepth conversation about dollar figure."

Earlier on Saturday, Al Jazeera's Gabriel Elizondo, reporting from Washington, DC, had said there were no signs that any progress will be made at the talks.

"He [Pence] hasn't come out and given any information, we're not expecting to hear any new information from him, so right now, there's a meeting, talks are going on, but the key people in this - President Donald Trump and Nancy Pelosi, the Democratic speaker of the House - are not holding talks. and there's no indication that they are going to meet anytime soon and make any progress on this."

'Keep it shut for months or even years'

On Friday, Trump met congressional leaders from both parties as the shutdown hit the two-week mark amid an impasse over his demand for billions of dollars for a border wall with Mexico.

The standoff has prompted economic jitters and anxiety among some in Trump's own party.

"We won't be opening until it's solved," Trump said. "I don't call it a shutdown. I call it doing what you have to do for the benefit and the safety of our country."

The US president reportedly said he preferred to call the action a "strike".

Trump said he could declare a national emergency to build the wall without congressional approval, but would first try a "negotiated process".

The US president also said the hundreds of thousands of federal workers who are furloughed or working without pay would want him to "keep going" and fight for border security.

Asked how people would manage without a financial safety net, he declared, "The safety net is going to be having a strong border because we're going to be safe."

Security officers at US airports have reportedly been calling in sick in droves since the shutdown began and their paycheques stopped rolling in.