The US government has begun shutting down many of its services after the Senate failed to agree on a new budget.
A bill to fund the federal government until 16 February did not receive the required 60 votes amid a bitter dispute over immigration and border security.
It is the first shutdown ever to happen while the same party, the Republicans, controls Congress and the White House.
The impasse will affect hundreds of thousands of federal workers, and the recriminations have already begun.
The White House accused Democrats of “[putting] politics above our national security, military families, vulnerable children, and our country’s ability to serve all Americans”.
But the leading Senate Democrat, Chuck Schumer, said President Trump had turned down two bipartisan compromise deals and “did not press his party in Congress”.
The last government shutdown was in 2013, and lasted for 16 days.
What is a government shutdown?
As of 00:01 Saturday (05:01 GMT), many federal agencies are no longer open for business – although essential services will continue to run.
Most staff in the departments of housing, environment, education and commerce will stay at home. Half of workers in the treasury, health, defence and transportation departments will also not be going to work on Monday.
National parks and monuments could face closure, which provoked an angry public reaction during the 2013 shutdown.
Visa and passport processing could also be delayed.
But essential services that protect “life or human property” will continue, including national security, postal services, air traffic control, inpatient medical services, emergency outpatient medicine, disaster assistance, prisons, taxation and electricity generation.