A scheduled meeting of the Stormont Assembly has been postponed amid intensive last-ditch negotiations to restore powersharing before today's 4pm deadline.
The Assembly had been due to convene at noon to begin nominating devolved ministers to a coalition government.
After a meeting of party whips, the start time was scrapped. It is understood the majority of the parties wanted to postpone the session until 2pm, but the DUP argued that the meeting should not proceed at all.
The whips are due to meet again at 1pm to make a final decision on the crucial sitting.
If the 4pm deadline passes, Northern Ireland faces the prospect of some version of direct rule from Westminster or yet another snap Assembly election.
SDLP leader Colum Eastwood said an 11th-hour agreement could still be struck.
"There is still time for a deal," he said.
"Last night, in an effort to further the process, the SDLP circulated another paper to all parties seeking agreement on a number of areas.
"Our efforts to aid a parallel process of engagement between all parties is an attempt to be constructive and to progress the talks to meet the deadline today.
"We will not be found wanting. We are here, as we have been for weeks, ready and willing to engage.
"I urge others now to get down to business."
Northern Ireland Secretary James Brokenshire has said failure to reach a deal would have "profound and serious" implications.
He is due to fly back to London at lunchtime to vote in the Queen's Speech debate at Westminster.
The key sticking point in the way of a deal has emerged as Sinn Fein's demands for an Irish Language Act, which would bestow official protection for Gaelic speakers.
The DUP is willing to legislate on the language issue, but only if Ulster Scots speakers are included in any Act, a condition Sinn Fein has rejected.
The institutions imploded in January when DUP leader Arlene Foster was forced from office after Sinn Fein's then deputy first minister, the late Martin McGuinness, quit in protest at the DUP's handling of the Renewable Heat Incentive (RHI) - a scheme that left the administration facing a £490 million overspend.
His move triggered a snap Assembly election in March.
A number of attempts to restore powersharing between the five main parties following that poll floundered, with three UK Government deadlines for a deal having already been missed.
Green Party NI leader Steven Agnew claimed the logjam essentially boiled down to the name of potential legislation that would protect Irish language rights.
Mr Agnew, who is not directly involved in the talks at Stormont but did attend the whips' meeting, said: "We seem to be arguing about the name on the face of a piece of legislation.
"It's about parties saving face, rather than parties trying to save the Assembly. And I think that's wrong and we should give the institutions the respect they deserve."
Prime Minister Theresa May's official spokesman said: "If, despite our collective efforts, it proves impossible to re-establish the executive, we will need to consider the options to ensure Northern Ireland has the political stability that it needs.
"In terms of what those options are, I wouldn't get into that at this stage."