The US government has entered another partial shutdown.
Congress failed to pass laws needed to fully fund the government after existing funding expired at midnight, local time (4pm Saturday, AEDT).
This is the third government shutdown since Donald Trump's re-election.
It is only a partial shutdown, so it will not be as extensive as last year's 43-day closure, but could still have significant impacts.
What's happening this time?
US government departments are funded under appropriations bills that are regularly passed by Congress.
Earlier this year, Congress passed the necessary bills to fund most government departments.
But funds for the Department of Homeland Security (DHS) were not included because Democrats refused to keep funding the agencies carrying out Mr Trump's immigration crackdown.
Prompted by the killings of Alex Pretti and Renee Good in Minnesota, the party is demanding specific changes to how Immigrations and Customs Enforcement (ICE) has been operating.
Until those changes are agreed to, Democrats say, they will not vote to fund the department.
So will ICE shut down?
No.
Even though ICE's annual funds have been blocked, it has plenty of money for now.
That's because of a huge funding boost delivered to ICE by the "One Big Beautiful Bill", which passed Congress in July last year.
It provided ICE with about $US75 billion ($106 billion) — more than seven times its usual annual budget of $US10 billion ($14 billion).
Customs and Border Patrol (CBP), which has been supporting the ICE operations, received an injection of $US12 billion ($17 billion) — a sum higher than its usual annual funding.
"Those agencies' missions will be largely unaffected by a shutdown," Republican congressman Mark Amodei said on Wednesday, when he chaired a congressional hearing on a shutdown's possible impacts.
What effect will the shutdown have then?
The funding lapse will affect other agencies within the DHS.
"The good work the department does outside of immigration enforcement will come to a screeching halt," Mr Amodei said.
Officials from those agencies outlined what that would look like at Wednesday's hearing.
Vice Admiral Thomas Allan from the US Coast Guard said a shutdown lasting more than a few days would delay pay for about 56,000 personnel.
"A shutdown also erodes mission readiness," he said, because training for air and boat crews would stop.
Sea patrols, fisheries enforcement and boat inspections will also be put on hold.
Gregg Phillips, from the Federal Emergency Management Agency (FEMA), said his agency was still responding to the severe winter weather emergency that recently hit 30 US states.
"FEMA's disaster relief fund has sufficient balances to continue emergency response activities for the foreseeable future," he said, but "if a catastrophic disaster occurred, the disaster relief fund would be seriously strained".
At the Cybersecurity and Infrastructure Security Agency (CISA), hundreds of staff would be furloughed, the committee heard.
But the US Secret Service will furlough only 6 per cent of staff.
"The pay cheques may stop, but the work will continue," deputy director Matthew Quinn said.
What about travel?
The travel industry is particularly worried about funds running out for the Transportation Security Agency (TSA), which runs airport screening and security.
The TSA said its 63,000 staff would not be paid until after the shutdown.
Acting TSA administrator Ha McNeill told this week's committee hearing that a lot of her staff "work pay cheque to pay cheque", and "many are still reeling" from the last shutdown.
"Many in our workforce were subject to late fees and penalties for missed bill payments, eviction notices, loss of long-term childcare arrangements, and more."
Historically, the delay in pay leads to more staff calling in sick. So the agency is warning of "noticeable impacts at airports, including delays, longer wait times and cancelled flights".
Travel industry groups called on Congress to urgently reconvene and fund the TSA.
In a joint statement, US Travel, Airlines for America and the American Hotel and Lodging Association said: "Travellers and the US economy cannot afford to have essential TSA personnel working without pay, which increases the risk of unscheduled absences and call outs, and ultimately can lead to higher wait times and missed or delayed flights."
What are Democrats demanding?
Earlier this month, Democratic leaders sent their Republican counterparts a list of 10 demands.
They included:
- Requiring agents to obtain warrants from courts before entering private properties, and to verify people are not US citizens before detaining them
- Ordering agents not to wear face masks
- Requiring agents to display ID
- Stopping raids at "sensitive locations" including hospitals, schools and churches
- No racial profiling, including questioning and searches based on a person's accent, language or ethnicity
- A "reasonable use of force" policy and expanded training
- Respecting the ability of state and local jurisdictions to investigate excessive force
- Minimum standards for detention centres, including allowing lawyers and members of Congress to visit
- No "paramilitary police", with standardised uniforms and equipment for DHS officers.
Another demand from Democrats was that agents wear body cameras, which Republicans agreed to.
ICE acting director Todd Lyons this week said more than 3,000 ICE agents now had cameras and another 6,000 were being deployed.
Where are negotiations up to?
Since Democrats released their list of demands, the two parties have been sending proposals back and forth.
The White House has been heavily involved.
The latest offer from the Republican side has not been released publicly.
But on Friday, house minority leader Hakeem Jeffries called it an "unserious offer" that "clearly omits things that need to happen", including the requirements for warrants.
He said house and senate Democrats would jointly respond "at some point".
"Then it will once again be in the hands of Donald Trump and Republicans to decide what's next."
Hours before the shutdown was set to kick in, US President Donald Trump said: "The Democrats have gone crazy."
"We'll see what happens," Mr Trump said. "We're talking."
When is this likely to end?
Members of Congress are now on a break and many of them have left Washington — a sign they are some way from a deal.
They are not due to return to the Capitol until February 23.
But they could be called back sooner if Democrats and Republicans reach an agreement.
"I have let people know to be available to get back here," Republican leader in the senate, John Thune, said.
Talks were expected to continue through the weekend.
