WASHINGTON (NYTIMES) - The spectre of a government shutdown is once again lurking in the nation's capital, just in time for the holidays.

Congress has until midnight on Friday (Dec 21) to avert a partial shutdown by passing either a series of appropriations bills to fund the Department of Homeland Security and eight other federal agencies, or a stop-gap spending measure to keep the agencies funded at current levels for a short period.

The US Senate approved a stopgap Bill on Wednesday that would keep the government funded through Feb 8 - and punt the impasse over a southern border wall to the new year and a divided Congress.

Republicans in the House of Representatives are scrambling to amend a Senate-passed Bill to appease President Donald Trump after he said he would not sign the Bill, clearing the measure for debate.

A subsequent vote was possible later on Thursday but it was unclear whether Republicans would be able to pass what Mr Trump wants.

If a shutdown were to take place, it would be limited in scope, according to CNN. That's because lawmakers have already funded roughly 75 per cent of the federal government through September 2019.

But a partial shutdown would still inconvenience hundreds of thousands of federal workers and ordinary citizens just before the holiday season. If lawmakers cannot strike a deal with President Trump, a number of government entities would be affected by a lapse in funding.

Here's what to expect if government funding expires on Saturday.

Nine departments will close, and more than 420,000 people will work without pay

The US Treasury as well as the departments of Agriculture, Homeland Security, the Interior, State, Housing and Urban Development, Transportation, Commerce, and Justice will all shutter if Congress fails to pass seven remaining spending Bills, and hundreds of thousands of federal employees deemed "essential" - including correctional officers, US Customs and Border Protection agents and Weather Service forecasters - will be forced to work over the holidays without pay, according to data compiled by Senate Democrats.

With 90 per cent of their personnel considered essential, the Department of Homeland Security will be hit the hardest.

Nearly 54,000 Customs and Border Protection agents and 42,000 Coast Guard employees are projected to work without pay, and as travellers flood the nation's airports and train stations, 53,000 TSA agents will keep working, as will air traffic controllers and aviation and railroad safety inspectors.

Law enforcement officers at the Justice Department will also be expected to continue working over the holidays without pay, including nearly 17,000 correctional officers, 14,000 FBI agents, and 4,000 Drug Enforcement Administration agents.

And after a long year battling ferocious wildfires, about 5,000 firefighters with the US Forest Service will also remain on duty.

Congress passed five spending Bills earlier this year totalling nearly US$900 billion (S$1.23 trillion) of the US$1.2 trillion in federal agency operating expenses.

Those Bills funded the departments of Labour, Energy, Defence, Health and Human Services, Education, Veterans Affairs, and the legislative branch - so they will remain unaffected. Mandatory spending programmes like Social Security and Medicare also will continue.

National Parks in the US will likely close

With funding for the Department of the Interior slated to expire, all 58 of the country's national parks would shutter over the holidays. If you have tickets for the famed Bracebridge Dinner at the sumptuous Majestic Yosemite Hotel on Saturday, start thinking about alternative plans.

Tourists visiting the nation's capital would also find themselves shut out of many of the district's headline attractions, including the National Zoo and Smithsonian museums, the National Gallery of Art and the National Archives.

The Smithsonian museum may have the funds to remain open, staff said in a tweet, but like many of the agencies set to be impacted, will give updates as the deadline approaches.

Another 380,000 workers will be furloughed.

Hundreds of thousands of workers will be sidelined as a result of the shutdown, unable to go into work and receive pay until their departments are funded, according to figures compiled by Senate Democratic Appropriations Committee staff.

Almost 95 per cent of the staff at both the Department of Housing and Urban Development and the National Aeronautics and Space Administration will be furloughed, as will 86 per cent - or nearly 41,000 people - of the Department of Commerce. Also furloughed: 52,000 staff at the Internal Revenue Service.

Aspiring globe-trotters with old passports may be out of luck

Funding for the US State Department is also set to expire on Friday, which could throw a wrench in the plans of international travellers who suddenly realise their passport has expired or who are looking to get a new one.

Visa and passport services will continue "as long as there are sufficient fees to support operations", a department spokesman said, adding that passport agencies located in government buildings affected by a lapse in appropriations may become "unavailable to the public".

Purchasing a new house may be harder

The Federal Housing Administration will likely see significant delays in loan processing and approvals, meaning any new homeowners may be placed on standby, and payments to roughly 3,000 public housing agencies will be delayed.

"With each day the shutdown continues, we can expect an increase in the impacts on potential homeowners, home sellers and the entire housing market," the agency previously warned in advance of a prior shutdown.

"A protracted shutdown could see a decline in home sales."