US President Donald Trump has met Democratic Senate leader Chuck Schumer at the White House to search for ways to avert a US government shutdown, as the clock ticks towards a deadline to pass a funding bill.

Key points: Democrats will not support the bill without protections for young immigrants

Democrats will not support the bill without protections for young immigrants If the government shuts down, only "essential" employees for safety and security will keep working

If the government shuts down, only "essential" employees for safety and security will keep working A shutdown has only happened three times in a meaningful way since 1995

A stopgap bill to fund the US Government through to February 16 appears on the verge of collapse in the Senate, where Democratic votes are needed to pass it before the deadline this afternoon.

Mr Trump said the meeting was "excellent" and that efforts were continuing, and called for a four-week extension to avoid shutdown.

"Making progress — four week extension would be best!" he tweeted.

However, Senator Schumer said disagreements remained after the 90-mintue meeting, which he described as "long and detailed".

"We discussed all of the major outstanding issues. We made some progress, but we still have a good number of disagreements. The discussions will continue," Senator Schumer said.

Shortly after Mr Trump's tweet, White House budget director Mike Mulvaney told CNN he expected an agreement would be reached in the next 24 hours, meaning the government would shut down at midnight but be reopened over the weekend.

White House budget director Mick Mulvaney said the likelihood of a government shutdown could be a 50-50 possibility. ( AP: Pablo Martinez Monsivais )

If the government shuts down, which has only happened three times in a meaningful way since 1995, hundreds of thousands of "non-essential" federal workers may be put on furlough, while "essential" employees, dealing with public safety and national security, would keep working.

The draft budget was approved by the House of Representatives, but the bill now has to be passed by the Senate

The Democrats have said they will not support the bill unless there are protections for young immigrants who came to the US illegally as children, known as "Dreamers".

Before meeting with Mr Trump, Senator Schumer said the Republicans were to blame for the stalled negotiations.

"We all know what the problem is — it is complete disarray on the Republicans' side," he said.

"The bottom line is very simple — our leader, our Republican leader has said that he will not negotiate until he knows where President Trump stands. That's why negotiations haven't gotten anywhere."

Congress has been struggling for months to agree on long-term government funding levels but has been side-tracked by the dispute on immigration.

The Government has been operating on a third temporary funding measure since the new fiscal year began in October

In a morning tweet, Mr Trump, who postponed plans to leave Washington amid the looming shutdown, accused Democrats of holding up the measure.

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Republicans control the Senate but with Senator John McCain undergoing cancer treatment at home in Arizona, they will need at least 10 Democrats to reach the 60 votes required to pass a spending bill.

In addition to strong Democratic opposition, at least three Republican senators have said they will not back the continuing resolution in its current form.

Mr Trump has accused the Democrats of holding up the budget

Amid the deadlock, more senators were raising the possibility of merely approving enough new federal funds for a few days.

The idea is to put pressure on negotiators to then cut deals on immigration, defence spending and non-defence funding by next week.

But Senate Republican Leader Mitch McConnell shot down that plan yesterday.

"Let's fund the government for a full month so we can actually get something done" and negotiate other issues including immigration, he said.

Senate Leader Mitch McConnell is pushing for a full month of funding, if a stopgap deal is necessary. ( AP: J Scott Applewhite )

Dick Durbin, the number two Senate Democrat, urged Republicans to sit down and negotiate on immigration and called on the House to stay in session until there was a resolution.

"We don't want to shut down the government," he said.

The immigration fight is over Democrats' demand that 700,000 young undocumented immigrants be protected from deportation.

Those children, known as "Dreamers," were brought into the United States as children, largely from Mexico and Central America, and given temporary legal status under a program started by former president Barack Obama.

Many have been educated in the United States and know no other country.

In September, Mr Trump announced he was ending the program and giving Congress until March 5 to come up with a legislative replacement.

In a late-night speech on the Senate floor, Mr McConnell accused Democrats of aiming to "hold the entire country hostage" by demanding immediate resolution of a "non-imminent problem" related to immigration.

ABC/Reuters