Last-ditch efforts are being made in Washington to prevent a shutdown of the US government.
With a Senate vote due shortly before the Friday midnight deadline, Republicans leaders are struggling to gather support to pass a budget bill.
The House of Representatives voted 230-197 on Thursday night to extend funding until next month.
President Donald Trump has called off a trip to his Florida golf club this weekend until a deal can be struck.
He invited Democratic Senate leader Chuck Schumer, a fellow New Yorker, to the White House for last-ditch talks.
Emerging about an hour later, Mr Schumer told reporters “some progress” had been made, but a “good number of disagreements” remained, including a difference in opinion regarding the Democrats’ desire to extend talks for another five days.
Instead, the president encouraged a four-week extension of federal funding but tweeted that the preliminary meeting was “excellent” and that they were “making progress”.
However, a few hours later he sounded more pessimistic, tweeting that it was “not looking good for our great Military or Safety & Security on the very dangerous Southern Border”.
What is this bill?
This would be the fourth short-term budget measure to squeeze through a gridlocked Congress since the fiscal year began in October.
Federal agencies are funded through annual budget appropriations bills.
But at the moment Capitol Hill is too engulfed by rancour over how the cash should be spent to agree a longer-term package.
This current bill would only keep the government funded until 16 February – so the whole drama may be replayed in the coming weeks.
Can it pass the Senate?
Right now, no – the budget package doesn’t have the 60 required votes.
Republicans only have 51 seats in the 100-member chamber.
But with hours to go until funding expires, there are a maximum of 47 Republicans in favour. Despite conservative pleas for unity so they can blame any shutdown on Democrats, three Republican senators are leaning ‘no’.
Lindsey Graham, of South Carolina, says he is opposed because he wants more military spending and an immigration deal. Rand Paul, of Kentucky, is citing concerns about the federal debt. And Jeff Flake, of Arizona, said on Thursday night he was not “inclined” to vote for the short-term bill.
He is backing a Democratic plan to approve enough federal funds for a few more days to allow both sides to negotiate a longer-term fix.
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So to get through, the bill would need a dozen Democrats, out of 49.
But only three Democrats – Joe Manchin of West Virginia, Joe Donnelly of Indiana and Doug Jones of Alabama – have so far said that they are leaning in favour.
The legislative brinkmanship looks likely to go right down to the wire.
What’s the problem?
The main bone of contention has been Democrats’ demands for more than 700,000 undocumented immigrants who entered the US as children to be protected from deportation.
These “Dreamers”, as they are known, were granted temporary legal status under a programme established by former President Barack Obama.
In September, Mr Trump announced he was ending the programme and allowing Congress until March to come up with a replacement.
The Republican president and congressional conservatives have been using the issue as a bargaining chip in an attempt to wring concessions from Democrats.
Mr Trump wants funding for tough new border controls, including his proposed US-Mexico wall.
Republicans have added to the bill a sweetener in the form of a six-year extension to a health insurance programme for children in lower-income families.
They are essentially daring Democrats to vote against a measure that has been a longstanding liberal priority.
But Democrats say they want this programme extended permanently.
The legislative negotiations went up in flames last week after Mr Trump allegedly complained the US was letting in immigrants from certain “shithole countries”.
What could be the political fallout?
The blame game is already in full swing with neither party wishing to be held accountable for closing the government as midterm elections loom in November.
This would be the first shutdown while one party is in control of both chambers of Congress and the White House, which could be politically embarrassing for Republicans.
A new Washington Post-ABC poll suggests that by a 20-point margin more Americans blame President Trump and his party for the imbroglio, rather than Democrats.
But a shutdown would also be problematic for 10 Democratic senators who are up for re-election this year in states won by Mr Trump.
They would face voters this autumn amid a hail of attack ads claiming they closed the US government to help illegal immigrants.
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In a late-night speech on the Senate floor, top Republican Mitch McConnell accused Democrats of trying to “hold the entire country hostage”.
Mindful of the risks, Democrats have shifted their messaging in recent days to say their opposition is about much more than just immigration.
Democrats hope to make it instead about the president and Republicans’ ability to govern.
Tennessee Democrat Steve Cohen tweeted of Mr Trump: “This man doesn’t comprehend work ethic, the office of President, or duty to the country. He understands golf, ice cream, and Big Macs!”
What happens in a shutdown?
Many government offices would be shut. It’s estimated that about 800,000 out of 2.1 million civilian federal employees took a forced leave of absence during the 2013 shutdown, which lasted 16 days.
But essential services would still run. That includes national security, post, air traffic control, inpatient medical services, emergency outpatient medicine, disaster assistance, prisons, taxation and electricity production.
US Defence Secretary Jim Mattis said that over 50% of his department would not go to work, and some maintenance, training and intelligence operations would come to a halt.
“We do a lot of intelligence operations around the world and they cost money, these obviously would stop,” Mr Mattis said when asked about the impending shutdown, “it’s got a huge morale impact.”
National parks and monuments could face closure, which provoked an angry public reaction during the last shutdown.
The Trump administration is reportedly making contingency plans to keep the parks running if no deal is reached.
Visa and passport processing could also be delayed.