London and Dublin said they still hoped Northern Ireland's political parties could strike a deal to form a power-sharing government in the province, just hours before their deadline expires Thursday.
After three months of negotiations to restore a semi-autonomous administration in Belfast, the squabbling was still continuing as the 4:00 pm (1500 GMT) deadline loomed.
If the parties cannot strike an agreement, the UK province will likely be fully governed from London, although Britain is being non-committal on its options.
Britain's Northern Ireland Secretary James Brokenshire and the Republic of Ireland's Foreign Secretary Simon Coveney have been facilitating the talks in Belfast.
"I believe that a resolution can be found and I'm urging the parties to continue focusing all of their efforts on achieving this," Brokenshire told reporters with less than four hours to go.
Coveney added: "Significant progress has been made, although there still remain gaps to be bridged on some key issues."
The power-sharing Northern Ireland Assembly is a cornerstone of a peace process that ended three decades of violent conflict in the province, broadly split between Catholic Irish nationalists and Protestants backing the union with Britain.
The assembly has powers over issues including health, education, justice and the province's economy.
Tensions between the two main parties boiled over in January and the Irish republican Sinn Fein pulled out of the executive.
That triggered a March 2 snap election in which the conservative Democratic Unionist Party (DUP) saw its lead over Sinn Fein slashed.
- Irish language stumbling block -
However, the DUP is feeling emboldened since Monday when it agreed a deal in the British parliament in London with Prime Minister Theresa May's Conservative Party to prop up her minority government.
In return, the DUP secured an extra £1.0 billion ($1.3 billion, 1.1 billion euros) for Northern Ireland out of British coffers over the next two years.
However, without an executive in Belfast, it could be London ministers and civil servants who decide how the cash is spent.
May's spokesman would not discuss what the options were if Thursday's talks fail.
"If, despite our collective efforts, it proves impossible to re-establish the executive, we'll need to consider the options to ensure Northern Ireland has the political stability that it needs," he said.
The DUP have indicated that they would agree to set up an executive then continue with talks on the sticking points.
The major bone of contention is Sinn Fein's demands for greater recognition of the Irish language, which the 2011 census found four percent in Northern Ireland could speak, read and write.
Unionists argue that this is unnecessary and could undermine British culture.
Sinn Fein's former regional development minster Conor Murphy said the party would not accept Northern Ireland being fully governed from London.
He told reporters it was "make up your mind time for the DUP", adding: "We want to get this business done."