A new vote is being held in the US House of Representatives among indications of a government shutdown beginning at midnight on Saturday, the media reported.
Faced with a rebellion by fellow hard-line Republicans, House Speaker Kevin McCarthy is trying to secure agreement on a temporary 45-day respite.
It's not clear if the measure - stripped aid to Ukraine - will pass, the BBC reported.
The fourth shutdown to occur over the past decade, it could affect everything from air travel to marriage licenses.
Most government employees will be furloughed without pay, and crucial nutrition programmes will be halted, the BBC reported.
It follows a hard-right revolt in the US House of Representatives.
Republicans control the House by a slim majority, while Democrats hold the Senate by a single seat.
That means spending bills to keep the government open require buy-in from both parties in order to advance through both chambers to President Joe Biden's desk.
On Saturday morning, Speaker McCarthy said he would put a 45-day continuing resolution (CR) plan to the floor -- a stop-gap would keep federal agencies open until Congress can agree on a new funding bill, the BBC reported.
The CR would include disaster relief funding, but would not include US foreign aid for Ukraine, which Democrats have been insisting on.
A rebel faction of right-wing Republicans has, so far, held up negotiations in the House, the lower congressional chamber, with a demand for significant cuts in spending, including a call for no more US funding of the war in Ukraine.
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